Experiments have proved lack of sleep as a cause of death. Lab mice that are deprived of sleep for three to four consecutive days eventually die. Lack of sleep for a long period of time, especially when combined with excessive fatigue, poses a serious threat to our health.

There are intensive research efforts to understand the mysterious workings of the biological mechanisms underlying sleep. Human beings spend almost a third of their lives in sleep. Yet, the basic sleep mechanism and its functions are still not completely known. Each of many theories proposed for understanding the secrets of sleep provide different evidence, but no guaranteed results have been attained so far. Initially, sleep was considered a rest period. However, although brain activity lowers during sleep, the brain continues actively working. It can be said that the brain rests itself by working during sleep.

Scientists classify a person’s state of consciousness as one of three stages:

1. Wakefulness
2. REM sleep
3. Deep sleep

According to this classification, sleep is divided into deep sleep and REM (Rapid Eye Movement) sleep. During a night’s sleep, there is a loop of REM sleep and deep sleep. Approximately 90 minutes of deep sleep is followed by REM sleep, which lasts between 5 and 30 minutes. Approximately 75% of the total sleep span is deep sleep; 25% is REM sleep. REM sleep happens while slipping into sleep from wakefulness. Just before waking from sleep, a short-term REM is observed.

During the first hours of sleep, REM spans are shorter, and they grow longer during the last hours of sleep. If a person is extremely tired, they experience extremely short REM sleep spans within the first hour of their sleep. They may even slip into deep sleep without REM. Right after mid-sleep, REM sleep periods last longer. If a person is deprived of all or partial sleep – such as the deep sleep or REM – they will need to sleep longer at the next opportunity. If they are deprived of REM sleep or deep sleep for longer periods, they will have longer deep sleep.

REM Sleep

REM (Rapid Eye Movement) is given this name due to the intensive and fast eye movements during this sleep stage. During REM, not only the eyes but also hands, arms, legs, and fingers move. An onlooker may think the sleeper is fully awake. However, scientists are unable to fully explain the reason why it is difficult waking a person in REM, although they are active as if they are awake – this is a paradox. In fact, a person in deep sleep may be awakened easier, by either sound or touch. If it is difficult to wake a person during the REM stages in their sleep, it may also be considered as a paradox for that person to wake from REM sleep.

During REM sleep, contrary to rapid eye movements and gestures, a person’s muscles are extremely relaxed and soft, to the extent of a wrist drop. This is called REM paralysis.

The reasons, mechanisms, and even benefits of REM sleep are not known for certain. The newest theory in sleep research claims the relationship between REM sleep and acetylcholine secretion. Acetylcholine is a brain hormone that triggers movement. Yet, acetylcholine typically causes wakefulness. This, too, appears as another paradox.

Dreams seen during the REM stage are remembered more clearly. The limbic system, including the hippocampus and amygdala, is active during REM sleep, thus it is assumed that it is easier to commit dreams to memory during this stage. The hippocampus is tasked with committing (reinforcing) information.

During REM sleep, a person’s heartbeat and breathing are more frequent and irregular. This also relates to what a person sees in their dream. During this stage, the basal metabolism rate is higher or equal to that of wakefulness. Electroencephalography (EEG) readings register beta waves, which normally show during wakefulness. Alpha waves show during times of calm, when the brain rests during wakefulness, such as at times when one closes their eyes and dispels thoughts. However, when the brain is actively dealing with an issue or when a person experiences an upset, beta waves appear. Beta waves also show during REM stage. This shows that the brain is active during REM stage.

Deep sleep

This stage of sleep is also called low wave sleep or delta sleep. During this stage, movements are at minimum, and the muscle tone is harder. Heartbeat, breathing, basic metabolic rate, and blood pressure are low. Internal organs like the stomach, intestines, urinary tract, and even the liver minimize their activities and slip into an actual rest.

During this stage, dreams and even nightmares may also be seen. However, one cannot remember a majority of dreams when they wake up. It is assumed that the traffic between the cortex and the lower structures of the brain are disengaged during the deep sleep stage. People wake up from nightmares, only to usually remember the last part.

EEG readings during deep sleep stage show delta waves. The presence of delta waves hints at the disengaged traffic between the cortex and the lower nervous system components (thalamus, hypothalamus, brain stem, hippocampus). This condition also shows that the person is in deep rest, free from pain and other bodily stimuli.

Secreted at night, melatonin is a hormone that protects against cancer and slows down the aging process. Melatonin also plays a role in lowering bad cholesterol (LDL) and balancing body heat and blood pressure. Melatonin secretion starts around 10:00 p.m. and reaches its maximum around 5:00 a.m. That’s why, the most ideal sleep is after 10:00 p.m. when melatonin secretion starts. Bedside lamps are not suggested as they hinder the secretion of this night-bound hormone. People should also avoid conditions such as stress, smoking, extreme lighting, lack of adequate daylight, and working at lengthy periods, which lower melatonin level.

We woke at the thud, panicked.

My wife and I had been dozing in bed, squeezing the last seconds of sleep out of our pillows before the inevitable onslaught of little people. It’s something of a delicious defeat when you hear the door creak open and steps on the carpet. You know you’re trading something so precious to you (sleep) for someone so precious, who you just wish would be precious elsewhere. But then they’re all warm and soft and tousle-headed and snuggly and saying things like “daddy, can we have special cereal?” and poking their knees into your side and sitting on your face with a full diaper and sticking cold toes into your armpits.

This morning they didn’t get to do all those precious, horrible things to us because we woke up to the sound of something thwacking against our window. After shaking off the confusion (no, it’s not a child on the roof; they can’t reach the window), I recalled why I knew the sound. It was a bird. And from the sound, a pretty sizable one.

I said as much to my wife, as I tried to open my eyes but managed only a half-squint. She half-muttered sympathy, as if she cared deeply inside but couldn’t get past the early morning fog. I added that since it was a big bird, it probably got away a little dazed, no harm done. I tried to find her to give her a reassuring pat, but I was too drowsy and missed completely. I also couldn’t pry my eyelids open still; they ached a little, as if I hadn’t used them for a week instead of approximately six hours.

I’ve read that birds, reptiles, and some mammals have something called a nictitating membrane, a third eyelid that acts as a translucent shield when they are diving or flying. They can draw it horizontally across each eye to moisten and protect it. For instance, many birds use it when they are regurgitating food for their kids so they don’t get their eyes poked out by little beaks.

I think of things like this when I’m abruptly disturbed from sleep. Things like this, and demonic children’s songs that will not be exorcised for hours.

We turned over and buried ourselves in the blankets for three more minutes before the precious, horrible people came and got us.

Nadia was playing hopscotch out on the sidewalk later in the morning when she found the bird. Robins are always the first birds my children encounter and remember. It was easy for her to name the body she stumbled upon, one story below our window, and quite dead. We had a little flurry of don’t-touch-that’s and daddy-is-it-going-to-be-okay’s, and I managed to deposit it into a small terrarium for them to look at. Animals can die of diseases communicable to humans, but this one died upon impact, and it was still warm. So the kids and I examined it carefully.

It was larger than any bird I’d seen this close. The wings were tucked in beside its impossibly light body. Many of its bones were hollow, for ease of flight. The neck was at a weird angle, a wrong angle. The death in front of me was at a wrong angle. It always has been, but it just felt much more wrong suddenly, because it was also in front of my children. Blood speckled its beak, a dark decoration above the warm red tinges on its chest.

I realized that it was a young one, probably a teenager in robin years. Its feathers were perfect, straight and sleek, pinions just slightly larger and smaller on each side, forming beautiful strong wings. And the roses on the sides under the wings were just barely forming up into a speckled breast. It was about the size of an adult but without the experience, which is why it probably hit our window.

One eye was slightly open and looking like black jelly, like it would spill out of the socket as liquid if you tipped the bird over slightly. The other eye was closed. This teenage robin had eyelashes on the under-lid. It had whiskers. Its feet were curled and delicate.

It was too beautiful. It was too sad.

Nadia was watching me. She told me she was sorry that it died because she could see the sadness in my eyes; but I wasn’t really mourning after the bird. We touched its wings, feeling its perfect form beneath our fingers: the surreal softness, the preciousness of a young fleeting life snuffed out. Not a sparrow falls but that He sees it. God saw this.

Woodpeckers will close their nictitating membrane, then tighten it a millisecond before they hit the tree so that their eyeballs don’t fall out on impact. Perhaps we need similar shields.

Only a few days earlier we had discovered a young robin hopping around the pine tree down in the yard. We took pictures. The kids enjoyed watching it hop around. There was a hawk above, circling around, and I like to think we saved that little robin’s life. There was a little one then, alive and bouncing, and then a bigger one, dead and stiff.

God saw this.

What is it about seeing that is comforting? Wouldn’t catching the sparrow be more comforting? Wouldn’t solving the problem, ending the great horror – death – wouldn’t this be a more lasting comfort? You see me, God. You see my children. But if you were to let them fall…

Sharks close their third eyelid when they attack. This way they can see their victims without getting blood in their eyes.

Kai got out of the house when he was only one year old. We noticed when it was too quiet. He had slipped out the screen door moments after I arrived home from work, and neither Linnea nor I had seen him. I locked the door. It was five minutes before we noticed he was gone, and in those five minutes he was down the outer stairs of the apartment building and toddling along the street.

The terror in my heart: I was running down the sidewalk in my dress slacks, socks, and undershirt, desperately looking for my son, expecting to see him lying in the street, expecting to be one of those parents we pray for, expecting to live with the knowledge that we didn’t see him, we didn’t see him, and then it was too late to see him…

He liked stairs, so he had kept to the house side of the sidewalk, and a kind and observant couple had pulled over and were with him four houses down when I ran up. The man was on the phone with the police, and I heard him say, “Oh never mind, it’s okay. The father’s here.” I thanked them, breathless, and held my son, and held him walking back, and held him up the stairs, and held him for another hour until he didn’t want to be held anymore, promising him I would see him, always, I would see him.

God saw this. How can I say it differently, to ease the pain? God sees… me?

If we mourn this way, how must God mourn at all He sees, at all the flickering lights snuffed out, the bruised reeds broken, the sheep silent before the shearer? Death is nothing new to Him, and in fact, He knows it as an old friend, an old foe, better than us all.

Today, this day, my children are alive and real, perfect in form and surreally soft. They are the preciousness of young life, fleeting, and my God sees them. Lest you think me morbid, think on why this is precious, why as a parent, as a child, as a human I am determined to cherish this thing we call life, why I must defend it for those I love, why death is such an aberration and a destiny and a defeated foe. The thought of death is morbid, maybe, but so is the thought of life without the thought of death. For now, we need both. And God sees us, in both.

God sees us.

Peregrine falcons see too, because as they dive at over 200 miles per hour, they blink their nictitating membranes repeatedly to clear away the debris and clean each eye.

In the midst of holding onto my family’s break-neck life, I find that I am unable to bring myself to accept such a thing as death, and yet… I know that it’s what I must do, for we will all encounter it, sooner or later. This dark thing I wish to dismiss by forgetting, or fighting, or examining on the operating table of a small terrarium: Death will come for us all.  I know, in my spirit, it is good – a gift given so that our difficult, fallen lives will not last forever, but it will never lose its dread, even when it has lost its sting. And perhaps I will embrace it as a friend when more years have passed beneath my feet, or perhaps I will embrace my Savior, and He will carry me through it into the place where it cannot enter.

And my heart holds its breath for all the times I must try to prepare my children for that moment – the one I feel certain I will never be fully prepared for, the one that God sees. I know I am actually only trying to prepare myself. I know it is not up to me, and I wish I could take more comfort in that. Perhaps someday I will. Every day is another reminder that I am not in control, and death is the great Out-of-My-Control.

But I know this. Each day that I walk in the sight of God, He will train my eyes, and my sight can be strengthened by seeing life and knowing it itself is but a shadow of the life to come.

Nadia, my little avian maven, knows that birds need nests. So she settles herself in a patch of fragrant clover and picks flowers as a pillow for the bird. She is kneeling in her pink flowered dress, a lily ringed with gingham, examining the ground and plucking appropriate stems carefully, precisely, preparing for burial. Perhaps, preparing for flight.

And I blink back a tear.

It was 3:45 pm. I was sitting crossed-legged with twenty other seven-year olds under a wall of flat glass windows. An eerie calm had settled outside, where a short time before there had been whipping winds and a sky as green as Kermit the Frog. My mom whisked into the building, her sensible yet fashionable heels clicking on the worn linoleum, and the petals of her flowered dress rippling with her gait. Shocked that I was not huddled in an enclosed room, she took one look at my position under the windows and told me it was time to go. That was the last time I ever saw my after-school program. Everyone knows not to take cover under glass during a tornado.

On the way home, my mom angled the car around downed branches the width of tree trunks and garbage cans lolling down the curb. The world was spent: siding dangled from the edge of condos, and telephone poles were precariously tilted, if they stood at all. People ambled about, assessing the damage as the neighborhood settled into a collective sigh. A policeman at the end of the lane directed traffic to make only a right turn onto the main street because of downed power lines to the left, the direction of our house. My mom said, exasperated, “Now we’ll never get home!” My mom, always tough and calm, was worried. It wasn’t until that moment that I got scared too.

We did, eventually, make our way to our still-intact home. Thinking back on that moment, one of a few post-tornado moments during my Indiana childhood, I note most how my fear was derived from my parents’ fear. I always felt safe and happy when at their side, but in the rare moments when they were fearful, I became beside myself with terror.

When I was growing up my mom and I would sometimes watch horror movies while sitting on our worn, brown suede couch. When the background music began its inevitable, this-is-the-scariest-part crescendo, I would turn my head 90 degrees to the right and look straight into my mom’s eyes. For the entire duration, my mom would calmly report that the masked man was bludgeoning the babysitter or wryly observe, “Oh, looks like the psycho wasn’t dead after all.” Sometimes she’d insert an, “Ew, gross!” exclamation when something bloody took her by surprise. I got all the emotion I could handle by looking into her eyes during those parts; she became a sort of “closed captioning” for me—recapping what my senses wouldn’t let me experience first-hand.

When I was a child and swam competitively for years with the local swim club, my parents attended every swim meet I participated in. They would sweat it out on the hot bleachers of the indoor pool deck, fanning themselves as they sat for hours in the backless bleachers waiting for my race to begin. If I became nervous before my event, as I always did, I’d scan the population of faces in ordered rows until I found my parents. My dad, always looking for me, would catch my eye and give me a thumbs up with a double eyebrow raise and a big smile for support. I would immediately feel relief and was instantly braver because he believed in me.

When I graduated from my small-town college and decided to move to New York City without a job, a friend, or a long-term place to stay, my parents took care not to discourage me. Instead, they threw an early birthday party for me and did the tough thing—they bought me luggage, in acceptance that I had to live my dreams, even if they took me far away from family. Upon unpacking that luggage, I found a tiny yellow post-it that my parents and older sister signed that said, “Love ya!!!” with each of their familiar signatures surrounding it. Beneath it was a card that said, “You Must Take Your Chance.” Never once did they remind me of my shy demeanor or annoying tendency to throw up repeatedly when travelling on my own. Never once did they ask me to stay with them forever, even though their eyes might have mentioned it.

 As an adult, I still gauge fear by my parents’ eyes. A few years ago, during a phone call that bridged the 1000-mile gap between our homes, my mom told me my dad was diagnosed with a brain tumor. She spoke flatly, like a tiny person standing in the mouth of a huge cave, every syllable clear and solitary. There were no reverberations, no hints of emotion. I tried to be the echo of her stillness. But when I arrived at my parent’s house and looked into my mom’s eyes, I knew we were in trouble.

The night before my dad’s brain surgery, he and I sat in cushioned deck chairs on the shaded back porch of the house. He looked intently into my face and asked if I thought he was doing the right thing by having surgery and if I thought he was going to be okay. His doctor had given him 6-12 months to live and flatly stated that this condition had a high mortality rate. Surgery could buy him time, but most likely he would not survive. My dad’s tumor gave him short term memory loss, so he forgot all of that. What he remembered was that he trusted me. What I knew was that every moment we’re given here on earth, we are living. If there was even a one percent chance that my dad would live, what’s to say he wouldn’t be in that one percent? Sitting on the porch that night, I breathed in, collecting all the calm I could from the cheerful summer day, erased fear from my face, and answered, “You’ve improved so much in this past week on medicine alone. I think you’re going to be fine.”

After his surgery, my mom, sister, and I walked down the hallway to see my dad in the intensive care unit. I have a nauseous fear of hospitals, one I inherited from my dad: a feeling that the hallway is too long, that the patients behind the floor-to-ceiling windows are unprotected so near to the thin glass walls, their bodies storming inside. We shakily entered Dad’s room, and he smiled at us and groggily said, “I feel fine,” then crossed his eyes and stuck out his tongue to prove his normalcy. I relaxed, seeing his face, seeing he was okay. I think he did it for that reason.

I guess that is what love is—reassuring each other in the eye of a storm, being the wall of calm and protective peace within the whirl of a tornado.

The eye is a miracle as it is. Even though we have a rough understanding of its basic anatomy, we are confronted with a much more complex miracle when we venture into the intricacies of its anatomy and the physiology of the act of seeing. We have theories about the many details – such as the perception and representation of mental images and their storage in the memory – but we still do not exactly know how the act of seeing works.

One of the most mysterious layers of the eye, the retina has an elaborate structure with a slew of functions. Not every eye surgeon dares touch the retina, which houses the most sensitive and special cellular layers. It is a three dimensional, crescent-shaped structure located in the back of the eye and is made up of ten super thin layers of cells that span the exterior part of the eye abutting the veins and its interiors.

Retinal layers

The ten layers that form the retina are:

1. Pigment (coloring matter) layer
2. Layer of rods and cones
3. External limiting membrane
4. Outer nuclear layer comprising rod and cone cells
5. Outer plexiform layer
6. Inner nuclear layer
7. Inner plexiform layer
8. Ganglion layer
9. Nerve fiber layer
10. Inner limiting membrane

These layers are incredibly sensitive and elaborate, and studying their intricate structure give a sense of awe.

Light for sight

Light first arrives at and penetrates through the cornea, the living glassy layer at the outermost layer of the eye. It then goes through the frontal fluid (aquesous humor) and the aperture called the pupil (pupilla). It hits the internal wall of the retina (the inside of the crescent) after passing through the lens in the eye and then the optic fluid filling up the chamber in the back. This alone is an interesting fact because it is much later that the light that gets to the retina reaches the layer of sensitive cone and rod cells, which perceive light. As these cone and rod cells are lined one after another for their protection, light reaches this outer layer of the retina after the ganglion cells, retinal layers and nuclear layers. Such an alignment leads to a reduction of acuity in the peripheral regions of the retina.

We have theories about the many details – such as the perception and representation of mental images and their storage in the memory – but we still do not exactly know how the act of seeing works

The central pit (fovea centralis)

The inner layers at the center of the retina, on the other hand, are drawn to the sides to prevent any loss in visual acuity. Resembling a pit, this section is much thinner than the periphery of the retina, so the layers that are likely to obstruct the passage of the light, and hence reduce visual acuity, are aligned specifically to allow light to directly hit cone and rod cells. Besides, cone cells, which are in charge of exact, colored sight, exist in this region, whereas rod cells, which are in charge of rough and uncolored (black and white) sight, do not.  The central pit where visual acuity is at its highest is for keen, colored, and exact sight. Why then is the rest of the retina not created for acute sight and why is this small section equipped with this ability?

As it turns out, if the entire retina had the ability to see keenly then it would not be possible for the eye to focus on a spot and accurately distinguish it from surrounding objects. If we could see the entire page of a book at a glance, for example, the lines would mix up in our brain. We would not be able to understand what we are reading. We normally start reading from the top of the written page and continue line by line as we focus on and take in each word. Our brain then can focus and perceive a single word accurately by restricting keen perception of the surrounding area.

The retinal pigment layer

The color black is known to absorb, not reflect, light. Thanks to such absorption, the layer made up of black pigments (melanin) or dyes prevents the reflection of light, which is crucial for visual acuity. This black substance functions like the black dye in the bellows of old cameras. If there were not any layer to absorb light, light would scatter off the wall inside the eyeball, thereby obscuring the sharpness between light and dark spots, which is essential for the formation of a clear image, and producing a blurry image due to the overall illumination of the retina.

People who lack this melanin pigment as a result of a genetic defect (Albinism disorder) have white hair, and they are oversensitive to light because the colored iris layer of the eye does not contain the melanin pigment, which refracts light. When an albino person enters a bright area, the light that hits the retina is reflected in all directions through the pigment-lacking retina and the white surfaces of the rigid layer underneath (sclera). Therefore, a ray of light that would normally stimulate a few cones or rods is scattered everywhere, stimulating all or most of the light receivers. As a result, visual acuity in albinos can only be between 20/100 and 20/200, even with the help of the best optical correction, which is a low value compared to 20/20 in normal sight. The joke that rabbits do not wear glasses because they eat carrots is based on the high concentration of vitamin A in this pigment, or black dye, layer of the eye. Indeed, vitamin A is a crucial factor for the health of these pigments.

Layer of rods and cones

Composed of 127 million light-sensitive receivers (photoreceptors), the retina is 0.2 mm thick at the yellow spot (macula lutea), where the image forms most clearly, and 0.1 mm thick at the edges of this area. The 120 million cylindrical rods in the retina are in charge of black and white sight (at twilight), and the 7 million tapered cones, of colored, colored and exact sight. The more common cylindrical rods are 50 µm (microns) in length and 1-5 µm in thickness. The less common cones are 40 µm (microns) in length and 3-5 µm in thickness.

The concentration of the cones increases toward the center of the retina and decreases toward the edges, to be outnumbered by the rods. In the cytoplasm of the cones and rods are stored substances that are sensitive to light (photosensitive) which break up when light contacts them and produce electricity in the cones and rods. In rods this chemical is called rhodopsin. In cones, on the other hand, are three substances corresponding to the colors red, green, and blue that are sensitive to the wavelengths of colored light. To be more exact, there are three separate cone cells that include one of these three substances. Chemically, the photosensitive substances in the cones are a little different from rhodopsins.

The destruction of rhodopsin by light energy

Rhodopsin, along with the color substances, fills up about 40% of rods and cones. They are made up of a protein called scotopsin and a molecule called retinene that is derived from vitamin A. When light energy is absorbed by rhodopsin or the color substances, rhodopsin starts to fade in as fast as one trillionth of a second. The underlying reason for this is that the electrons in the retinene (vitamin A) part of rhodopsin is activated by light, which alters the shape of the retinal molecule at a mind-boggling speed (one trillionth of a second). Extremely complicated and precise chemical and physical changes then take place. It is very difficult to monitor all of these biochemical changes, and they require specialization [1].

The regeneration of the rhodopsin destroyed by light

Rhodopsin destroyed by light is regenerated in the dark. Only in the twentieth century did we manage to partially identify the mechanism by which molecules with very specific geometric shapes decay at incredible speeds only to be regenerated later. It is wondrous that such knowledge and power are present in the cell allowing the light energy to destroy the molecule and the regeneration process is launched. The circulation between destruction and regeneration of the molecule continues throughout a lifetime [2]. Vitamin A is assigned a crucial task in the generation of rhodopsin in the dark. All-trans retinal is converted in the retina into all-trans retinol, which is then converted into 11-cys retinol with the help of an isomerase enzyme. Finally, 11-cys retinol is converted into 11-cys retinal, which in turn combines with scotopsin to form rhodopsin. Vitamin A is present both in the cytoplasm of rods and in the pigment layer of the retina. In this way, vitamin A is kept in reserve to be used for generations of new retinal. If, on the other hand, there is an excess of vitamin A in the retina, the excess amount is converted into retinal, by which the amount of light-sensitive pigment in the retina is lowered.

Night blindness

Night blindness appears in anyone who suffers a serious deficiency of vitamin A. Because there is a lack of vitamin A to be converted into retinal, rhodopsin amounts decrease dramatically. This disease is called night blindness as it is noticeable only in the dark or at night and does not affect sight during the day, due to the reduction of light for proper seeing. In daylight, however, cones can still be stimulated despite a similar decrease in color pigments. Night blindness typically only appears in people that have a low vitamin A diet because huge reserves of vitamin A are normally stored in the liver to be used for the eyes.

The human retina contains 400,000 light receptive cells per square millimeter. For comparison, this number is 680,000 in the retina of the owl, which needs to perceive even the slightest glow when hunting in the night. As another example, with 397,000 such cells the amount in the cat’s retina is almost the same as ours.

An average of 130 sight cells in the retina are connected to a ganglion (nerve node) cell. Constituting the nerve of sight, or the optic nerve (nervus opticus), every nerve fiber is connected to a ganglion cell. It takes about 15-60 seconds for the retinal optic nerves to adapt from dark to light, while it takes as long as 30-45 minutes to adapt from light to dark. The visual range of optic cells, i.e. the lowest and highest amount of light the eye can perceive, is between 10^-7 and 10⁶ nanometers. Light that is below or above this range is invisible to us because of its insufficient or overwhelming wavelength.

All the colors we see in the world are named according to the wavelengths absorbed and reflected by optic cells. The spectrum of the optic cells lies between red and violet, which is the limit of visible light for humans. Light with a wavelength of 400 nm is perceived as violet, while light with a wavelength of 760 nm is perceived as red. Our eyes cannot see infrared and ultraviolet light. Some animals, however, are known to see light beyond these limits. For example, we know that bees can see certain shades of ultraviolet light, which helps them find flowers to pollenate.

Clearly, it is not an easy job to elaborate on the divine art manifested in such a small area as the retina. Complicated structures and reactions that require specialization even to comprehend keep taking place smoothly every moment we look around. At least we can be thankful for this amazing gift of vision given to us free of charge so that we can recognize the universe.

Notes

[1] It causes the cys form of the molecule to change into the all-trans form. Although the all-trans form has the same chemical structure as the cys form, its chemical structure is different in that it is a flat rather than angular molecule. With the impact of light photons, the position of the molecule in space changes, yet its chemical composition remains the same. Because the position of the reactive regions of all-trans retinal no longer fit in with the reactive regions on scotopsin protein, the molecule is pulled off. The product that forms at that moment is batorhodopsins, which is a partly destroyed combination of all-trans retinal and scotopsin. An extremely unstable compound, batorhodopsin turns into lumirhodopsin in nanoseconds, into metarhodopsin I in microseconds, into metarhodopsin II in about one millisecond, and finally into decomposed products, scotopsin and all-trans retinal much more slowly (in seconds).

[2] The first step in the reformation of rhodopsin is the recycling of all-trans retinal into 11-cys retinal, which requires ATP energy and is catalyzed by retinal isomerase enzyme. Once created, 11-cys retinal combines with scotopsin to form rhodopsin.

How can animals in the wild hunt during the night as if it were day? A remarkable biological feature acts as a pair of “natural” night vision goggles.

Animals can move and even hunt in the pitch-dark of the night. How do these animals see comfortably in the dark? How are their eyes different from ours?

Anatomically, the eye consists of three layers called the Tunica fibrosa (outer layer), the Tunica vasculosa (mid layer), and the Tunica nervosa (retina). The outer layer of the eye is composed of the sclera and cornea; the middle section of choroidea, corpus ciliare, and the iris; and the inner section of the retina.

Light rays reflected off objects first pass through the eye’s translucent layer (the cornea), then into the black round part located in the front of the eye (pupillae, or pupil), and later go through the lenses. The colored section around the pupil, covered by smooth muscles, is in charge of regulating the amount of light entering the eye. The real and inverted image of an object is projected on the retina by the refraction of light through the lens; the image is transmitted to the optical center of the brain as a result of nerve cell stimulation via the optical nerves. Sight happens as a result of these causal chains.

Now, there is a twist to all this: the optical center in the brain accepts spots that do not emit light as black. For humans, this means a loss of sight. Black objects are not visible because they absorb and keep all the light reaching them.

How could these animals, without night vision goggles, see in pitch blackness despite having the same optical mechanisms as humans?

The answer to this question was hidden in an anatomic structure (tapetum lucidum) located in the eyes of some vertebrates. This special structure, lacking in humans, monkeys, squirrels, birds, red kangaroos, and some other mammals, is found in equines, ruminants, and many carnivores. This structure is located in the cytoplasm of the choroidea layers in between the innermost light sensitive ocular layer and sclera, and it acts like a biological reflector. With its crystalline composition of varying colors from golden yellow to white, tapetum lucidum is a wonder of creation. The eyes of these animals shine when a light source is projected due to the aforementioned structure.

The primary task of this formation is to reflect the light which is projected to the rear section of the eye again without absorbing it. This happens due to the crystalline makeup. Thus, lower light levels are enhanced by the repeated reflection in the eye, and sight is enabled for animals. The second job of Tapetum lucidum is to elevate the sensitivity of the retina to light in order to transmit signals with no stimulation strength to the optical center.

This reminds us of night vision goggles. Night vision cameras are electro-optical devices that strengthen the light that is present. Light enters this device through the lens and hits the charged cathode, which has a lot of high energy. The energy load hits the phosphorous screen where the image is focused after passing through the vacuum inside the charger. The image is an enhanced picture on the phosphorous screen and it is not visible directly through the object. Tapetum lucidum however, is such an artistic work that it cannot even be compared with the night vision systems of technology. While the lifespan of a night vision system is only 2,500–4,000 hours (104–167 days), animals with Tapetum lucidum can benefit from this for a lifetime. The newest night vision systems, with a maximum optic range of 30-120 meters, cannot provide sight under light conditions one fourth of the moon’s illumination strength, whereas animals with Tapetum lucidum can see objects hundreds of meters away in much dimmer light.

This isn’t the only example of how masterfully and diverse eyes can be. Damseflies have over 30,000 simple eyes, called ommatids; eagles can see their prey from thousands of feet above them.

By the principle that “certain things are appreciated best in their absence,” if we imagine a dark night in which we are unable to see anything and cannot even step a foot safely, we can perhaps understand that Tapetum lucidum is a great blessing for these animals.

Reference

Veterinary Ophthalmology (2004) 7, 1,11–22. Comparative morphology of the tapetum lucidum (among selected species), F. J. Ollivier,* D. A. Samuelson, D. E. Brooks, P. A.Lewis, M. E. Kallberg and A. M. Komáromy.

Flies have two wings that are capable of moving independently from each other; these wings go back and forth on a single axis during flight. Technically, the unequal angles of the wings to the abdominal region could have prevented flight. Yet in the case of flies, this abnormal situation is not a hindrance and results in a harmonious wing stroke.

Let’s bring our palms together over our head and then lower them near our legs. How many times can we make this movement in a second? Let’s say two, three, or maybe four times if we are really quick. Flies have the ability to stroke their wings hundreds of times in just a second. There are benefits associated with this series of movements. The surface of the wings and the rear section of the head are equipped with sensitive hairs that are in charge of registering air currents and mechanical pressures and conducting relevant flight data to the brain. The unwanted effects of air currents towards the body surface and wings during the flight are detected via these hairs that house receptors. Thus, the wings are controlled according to the signals arriving from the brain. Therefore, a fly can feel an air curtain (like an insect screen) against it instantly and often times flies away. Sometimes, they also stroke their wings hundreds of times per second to avoid the negative effects of air resistance on the wings. Without these receptors and serial wing movements, the air current would stick to the wing’s surface and would not let the fly, well, fly.

Is it a fly or a plane?

We sometimes witness comparisons between the flight specifications of planes and flies. However, it is a great injustice to the fly to be put in the same basket as a plane. The products of modern technology, such as a plane, are invented after drawing inspiration from the meaningful skills of animals like a fly. It is not possible to build planes with a wing width smaller than 15 centimeters; there are disadvantages to wings smaller than that in terms of generating lift. On the other hand, flies have much smaller and more fragile wing structures (relative to their bodies) and can maintain their flight in a perfect fashion. When a fly extends its rear legs, covered with hairs designed especially for cleaning the wings, and sweeps them over its wings, doesn’t this suggest a fly is more impressive than a plane?

It challenges mountaineers!

A fly challenges mountain climbers by easily moving on the four walls and ceiling of a room – and even on slippery surfaces like glass. What is its secret?

Its ability to stand or walk on the ceiling without being defeated by gravity is possible via some of its organs. The final sections of fly’s legs are like hooks and the tip of this hook is equipped with suction pads. When flies touch a surface, a sticky fluid is secreted from the suction pads. Flies can remain suspended on the ceiling with the help of this fluid. When it approaches the ceiling, extends its legs to the front and flips towards the opposite direction of its approach, it sticks to the ceiling on its abdomen.

The grand architecture in the eye of the fly

Can you complete a jigsaw puzzle of 8000 pieces in a second without any missing pieces? It seems impossible, but let’s accept that you have. Can you fit this puzzle into an area that’s just a couple of square millimeters? It’s not possible for a man of intelligence to pass this test. However, the fly completes this miraculous task every time it uses its eyes in our rooms. We are unaware of the fact that the fly, which draws patterns of colors under the sun light, has such amazing eyes. Its eye is created to contain nearly 8000 ommatidium, which function almost as small eyes. Different areas can be seen via each ommatidium and once images are put together in the brain, the whole picture forms. Through these tiny eyes, shaped as hexagons that resemble honey combs, a fly can see as close as 2 mm – and can even see behind its body! Because of the wise hexagonal design, the ommatidia are placed in the most economical way possible; there are no missing spaces which could cause a lack of clarity. The optical speed of a fly’s eye is nearly 4-10 times faster than the human eye. Flies can see the ultraviolet section of the light spectrum and this allows them to evade predators easily in dim environments. Every time a fly uses its eyes, it’s as if it gives the message, “Look at how miraculously I’ve been created. Do you think that my creation could have been in vain?” Such complexity is an inspiration to scientists as they try to develop new technologies.

One of the features of flies that surprises scientists most is the way they use a neural network of a very limited number of neurons to perform so many complex movements. Biologist Michael Dickinson expresses his astonishment as to how a neural system of such small scale can accomplish all of these features.

Do not ever kill a fly!

Flies consume plenty of energy during flight. A regular supply of oxygen is needed to compensate for the energy they use. Air is inhaled via a constriction of the abdominal muscles when the fly lands on a surface. However, during the flight, air enters via the serial movements of the wings. Air that enters through the openings of the chitin layer surrounding the fly is transported to cells via small channels.

Flies locate their food via their smell receptors. Thus, a fly in the air easily lands on the food source that it detects. The taste organ detects whether the food is an ideal source or not. Usually, their choices of food are human foods, waste remains, and dirt. There are two tubes located in the mouth of the house fly. It sucks liquid food with one of the tubes; saliva containing enzymes is secreted on the food source with the other hose so that digestion is facilitated. A fly secretes plenty of saliva in order to liquefy the solid foods it prefers.

Flies that use dirt and waste as a nutritional source are considered as disease contracting pests. However, this is a major fallacy. Flies are actually the health officers of the ecosystem. They turn microorganisms ineffective as they take in their food; the digestive enzymes that they carry play role in completing this important task. Due to this important task, it should be remembered that killing a fly is very unfortunate. Great scholar, Bediuzzaman Said Nursi, notes that flies are assigned to terminate unhealthy microorganisms and materials.

Scientists led by Prof. Andy Beattie have noticed that flies are resistant to all kinds of dirt, including from meat and manure. He said that these organisms should be super resistant to infections, otherwise they could not survive and that our work to gain antibiotics from them has been partially successful. In fact, studies focused on obtaining antibiotics from flies started in the past century. English and Swedish scientists isolated certain antibiotics from flies in 1930 and 1947. Efforts to isolate antibiotics from flies continue today.

Reproduction in black flies!

Black flies reproduce quickly. In suitable humidity and temperature, eggs start to hatch in just 10 hours. Larvae feed on liquid materials, though they need bacteria living on solid food to convert it into liquid form. Therefore, an acid is secreted inside the digestive track of the fly that can terminate most of the bacteria. Thus, the insect becomes free of bacteria, ready to fly. One fly can lay more than 100 eggs at one time and between 600 and 1000 in their lifetime. They can lay eggs again after just three days.

When looking at the information we have, it’s clear that flies are acrobatic flight masters with mind blowing features. We should abandon the negativity towards flies and contemplate the perfection of creation by considering their many remarkable skills – and working to discover even more secrets about them.

Where am I?

There are 46 chromosomes in your body, carrying 20-25 thousand genes. Chromosomes and the genes they contain shape the genetic memory of a human being. Genes can contain hundreds of features, and these are revealed over time. For instance, you do not have any teeth when you are a newborn, but the time when you will get your teeth is encoded into your genetic memory. Once genes receive the action command, teeth start to emerge.

There are hundreds of genes located on chromosomes, all the way from the chromosome number 1 and 2, to chromosome number 46. For example, there are around three thousand genes found on chromosome number 1. The Y chromosome, in charge of male development, only contains 125 genes. A distinct address (locus) for each gene on the chromosomes is recorded. If you ask about the address of the fibrillin gene that synthesizes me, it is 15q 21.1, i.e., 15th Avenue, Long arm street, 21st pl, Number 1.

In other words my residing address is the 1st subband of the 1st band of the 2nd region located at the long arm of chromosome number 15. We are three siblings, known as fibrillin1, fibrillin2 and fibrillin3.

We stretch and relax like an arch. We can expand and tighten like an inflated balloon and then return to our previous state. If by an error, we happen to fail to restore ourselves after inflation, the tissue’s architecture gets deformed and expanded fibers cannot regain their original shape anymore. When observed in veins, this situation is called an aneurysm. The frequency of this disease is approximately one in ten thousand, which is also called ballooning. That said, my flexing is necessary. Veins flex so that the blood pumping through them doesn’t cause any turbulence, as it would otherwise be during a vacuum occurring inside metal water pipes. Flexible sportsmen who do acrobatic moves do not compare with me. I can bend, curve, flex, relax and constrict, inflate, deflate and transform like elastic, from one shape to another, for your health and overall convenience – all because of the wondrous features granted to my nature.

What kind of a fiber am I?

I provide structural support for the fabrication of elastic fibers in the connective tissue as a protein synthesized according to the code of the fibrillin gene. In case of my failure or absence, weaknesses occur, especially in the connective tissues of organs that are rich in elastic fibers, such as the aorta, lungs, and eye balls. The iris (the colored part of the eye), pupil, and eye lens display changes in accordance with levels of light or distance of objects observed. These changes are controlled perfectly according to my work, and humans often don’t even notice this. We also help the eye lens constrict and relax. It can be understood that we are such a great blessing granted for your service. Of course, if we tried to count all the blessings we’ve been given, and never even consider, it would be impossible!

My weight is 350 kilo daltons. A Dalton is an atomic mass unit approximately equal to one hydrogen atoms’ mass, which is 1.66×10-24. I consist of 2.871 amino acids. I am formed by the sequential arrangement of 20 amino acids that exist in your body as the smallest unit of proteins. We bind each other to become 10-12 nanometers wide microfibers as the result of a process called polymerization that brings loops of a protein chain together. These microfibers are brought together with the elastin protein that provides elasticity in our body. The system that we form with elastic fibrils constantly serves the body’s blood vessels, primarily the vessels located in your eyes, heart, and many of your tissues, such as your skin and nerves.

What do I do? We fulfill commands that are requested from us in many tissues and organs, without any flaws. Scientists call us the wonderful building blocks of the body’s architecture. We can extend twice as much of our length. We are always on task: while you are breathing, when your heart is pumping blood and your stomach is digesting food, or the moment you are gazing at nature with your eyes. We are given the duty to prevent many organs from tearing, including the heart, lungs, stomach, and blood vessels. One of the places I work most frequently is the aorta, the body’s major artery. Your heart beats approximately a hundred thousand times a day. A high level of pressure develops in the arteries during the pumping process. You would suffer greatly without the help of our elastic fibers. Blood vessels would rupture, ending your life. This high pressure is tolerated only through the expansion of the vessel’s diameter without any decrease in length of the artery. This diameter regulation is designed so wondrously that blood flow remains the same; no shaking or waves are observed. This diameter control happens via the fibrillin protein located inside the vessel.

I also play a role in the vitality and tension of your skin. Skin is essentially a dense fibrous connective tissue composed of a protein called collagen. I am also one of the main elements of this connective tissue. As you age, this layer starts to dry and has lesser fibrous proteins; therefore, as fibers decrease, so does my tension, and I start to wrinkle. Elderly people do not like getting wrinkly, but this is your fate. Whatever you do, I will also age and die.

I cannot go without pressing this important issue: Staying under the sun for a long time degrades me. If done properly, sun light is useful for skin. But solar radiation damages the live tissues and organs. This radiation is an effective factor both in degradation of protein structures, and the formation of varicose veins and skin damage. It is reported in various sources that exposure to sun rays leads to alterations in the genetic material of skin. Ultraviolet rays speed up the degradation of skin. In medical language, this is called oxidation via free radicals. Please do not burn us and yourself while sunbathing. Even if you do not care for yourselves, you should still be considerate of us. If you say that sunbathing both helps, with vitamin D synthesis and reducing the risk of osteoporosis, I would like to remind you that for the vitamin D synthesis of skin, it is sufficient to expose your hands, feet and face to the sun.

How is life without me?

Though we were wisely designed, sometimes, you are tested by certain diseases in which we are not present. Absence, as they say, makes the heart grow fonder!

Life without me is unbearable. I could give a couple of examples, should you like. If I was not created, your skin would not be flexible. You wouldn’t be able to control your eye lenses. Your aorta would not be flexible and your heart, which beats thousands of times a day, would be torn under the high pressure in a short amount of time. Major problems would occur with the development of your stomach, lungs, and other organs.

I also have a significant job keeping TGF-Beta (which helps cells grow) function under control. To give you an idea of how important this is, imagine your communication system turned upside down. Now imagine how complicated are the communication systems connecting billions of people around the world, how a mess it would be when they are out of service. These are nothing when compared to the human body. There are 100 trillion cells in the human body, communicating with each other instantaneously. A cellular community that is fifteen thousand times more crowded than the earth’s population communicates via small molecules, like us. Cellular proliferation and tissue differentiation would fail if cells failed to communicate. The full spoon of food in your hand would not end in your mouth but maybe in your ear or your eyes.

If a mutation happens with the Fibrillin-1 gene, Marfan syndrome can occur. This disease, which was defined in the 1800s, is named after its discoverer. The frequency of this disease is one in five thousand. One of the major lethal consequences of Marfan syndrome is an aorta tear. This is in addition to many problems with the eyes, skeleton, and cardio-vascular systems. Many of the patients die in their 30s or 40s because of the flaws in the cardio-vascular system. Of course, death may occur at any age because of an aorta rupture. 14% of the patients with Marfan syndrome display chronic obstructive pulmonary disease (COPD), which is associated with breathing problems, because the integrity of lung tissue is compromised. Another disease I help prevent is called Ektopia lentis, in which the eye lens is displaced from its original position. Normally, I help eye functioning. When my fibers relax or constrict, depending on light, I help the eye to relax, enabling both near and far sightedness. With Ektopia lentis, anomalies on the front vestibule of the eye, a high degree of myopia, and retina damage occur.

If overproduced, I can cause another problem with the eye, called exfoliation syndrome. This is when fibrous connective tissue, like me, accumulates in the eye – it’s commonly called glaucoma, or ocular hypertension. In some people, as they age, a fibrous material like hair dandruff collects on the eye lens. This material, dislocated by movements of the iris, blocks the drainage channels that discharge the intraocular fluid. Eye pressure increases as the result of failed drainage. As you see, I am not a problem when I am synthesized normally, but can be trouble if over produced! My final request from you!

You have seen our amazing works and complicated functions. Therefore, please remember me and my friends. Please do not ignore our efforts and activities. Be grateful for the blessings provided through us, even if you can’t see them. And take care of us, please – don’t get carried away with too much tanning!

In our times, the Big Bang Theory is generally accepted to be the starting point of the universe. When the Big Bang happened, the universe and light were simultaneously created. The universe came into being at elevated temperatures from a single particle.

For the events that happened after the Big Bang, the most recent and accepted theory is the Inflation Theory. According to this theory, right after the Big Bang, the universe started inflating at an incredible rate, quantum fluctuations were scattered throughout the universe, and a homogenous inflation happened which allowed galaxies to be formed. Light was created at this period for the very first time.

What is “light” and what is the wisdom behind it?

Ibn Sina was the first scientist stating is was possible to measure the speed of light. And Newton used the marble example to explain the phenomenon of light containing colors of different wavelengths. Modern theories state that light is composed of weightless and charge-less particles called photons. Light is now known to be electromagnetic waves that carry energy as well as having the characteristics of refraction and reflection. A major discovery occurred in 1975, when the Danish scientist Ole Romer was observing the satellites of Jupiter. During this study, he was able to prove that the particle model proved to be insufficient, as was seen from the diffraction of light (changing its direction after having passed a narrow slit)..

Although the wave model is more dominantly talked about in modern times, it is known that both models are true.

Femto photography

Various experiments have been done to understand the properties of light. One of these experiments was a photography technique applied by Dr. Edgerton, in 1964. In this photo, the image of the apple right after the bullet passed through it was captured. This famous photograph, which was captured in a millionth of a second, inspired Prof. Ramesh Raskar from MIT (USA) to take a photo of light in order to see it by naked eye. Raskar developed a camera that can take up to a trillion frames per second. This would make it possible to visualize the human body without using X-ray. The wave like property of light was studied by this new technology called Femto Photography.

Light is the fastest substance in the universe. As long as it does not change its environment, the movement of light is linear because of its electromagnetic wave properties. If it passes to a different but transparent environment, it continues its movement. If it passes to an environment where the refractive index is larger than its original environment, it comes closer to the line accepted to be vertical to the surface (normal) and vice versa.

The speed of light and all electromagnetic waves in an empty, airless environment is 299,792,458 m/s (300 thousands kilometers). With this incredible speed, the Earth could be toured 7 times a second. The letter c represents this speed in science, and it’s based on the Latin name for speed: celeritas. While passing through any object (air, water, glass etc.) the speed of light is smaller than c.

If a laser pointer is activated for a thousandth of a second (a couple of femto seconds), a photon cluster is formed which is approximately 1 mm in width. This cluster of photons has a speed millions of times greater than the bullet passing through the apple.

What if the femto photo of a cluster of photons that were sent from the bottom of a glass bottle full of water was taken? How would the light appear in slow motion? Although this short journey of light takes place in less than a nano-second, it is possible to capture how it moves in slow motion by reducing the speed ten billion times with the femto camera. With this femto camera, it is possible to measure the average speed of light in a tomato and gain knowledge about its interior texture and quality without touching it. When a bunch of photons are sent to the surface of a sample, a three dimensional picture of it can be constructed by the high resolution detection of the photons that are reflected at different times from the sample.

With the science of light, technology for transportation that does not require a driver can be developed, creatures can be saved from natural disasters by the reflection of light on windows, and many new age surgery technologies can be developed.

In order for the eye to see, light needs to exist. One of the latest and most astonishing pieces of research done about light is the femto photography technology. By this technology, it will be possible to visualize the human body without the use of X-ray. If there was a femto camera incorporated in our cell phones, we would be able to understand the quality of the tomatoes we were buying when we went to the grocery store without having to touch them. By harnessing the great gift of light, we can make the great gift of life even better.

There are so many blessings in life, granted to us free of charge, which we take for granted. Eyesight, being able to see near and far distances, most certainly tops the list. But we do not have to be deprived of our sight in order to understand its wisdom and functioning, and to contemplate upon its true value and worth.

Years of research and hard work were dedicated to develop cameras and multi-featured objective lenses. Initially, one to three lens objective cameras were used for simple shots, whereas today, objectives with seven to ten lenses are being used to take better photographs from a snow drop falling onto a flower to a buzzing bee resting on a flower. I wonder to what extent human beings are aware of the pair of eyes that has been bestowed upon them by God, and its ability to see different colors and shapes both near and far. Unfortunately, as people who often understand the true value of things once they are lost, we understand the blessing of being able to see near after the age of forty when we cannot read the newspaper without glasses and when we cannot put a thread through a needle.

So why is it that we can still see far after the age of forty but fail to see near? In order to understand this we need to examine the structure of the eye and its functions.

The structure of the eye and the ability to see

The exterior part of the eye is made up of a translucent layer (cornea) at the front and a white protective layer (sclera) behind it. The vascular layer of the eye (uvea) is located in the middle of the sclera. The most inner part of the eye is made up of the retina, the light-sensitive layer of tissue responsible for converting light rays into electrical signals. The hole located in the center of the iris, the colored part of the eye, is called the pupil. Behind the pupil is the crystalline lens. For a clear vision, lights reflected from objects need to be focused on the central part of the retina (fovea). While cameras have lens systems to focus the image on the film, it is the cornea and crystalline lens that are responsible for the same function in the eye.

Refraction power of cornea is constant and around 43 diopters. The refraction power of the eye lens when resting is around 20 diopters. Light rays coming from outside refracts at a set ratio and manages to focus on the retina. The light rays coming at the retina are then coded into electrical signals. Afterwards these signals are routed towards related regions of the brain via optic nerves. Most of the stimuli relayed by the optical nerve arrive at the visual center of the brain (occipital cortex). These coded electrical signals then become vision when they reach the optical lobe of the brain.

The function of the lens and accommodation

The refraction power of both the cornea and the lens (43+20+63 diopters) is sufficient to focus an image on the retina when looking at objects farther than 6 meters. Extra refraction power is needed for closer distances in order to focus images on the retina. Mobile lens systems enable this job to take place in camera objectives. Since refraction power of the cornea in human eye does not change, this additional task of refraction is set to be provided by the ocular lens. It is built as a flexible structure without any blood vessels. Aqueous humor (lens fluid) which is secreted by the ciliary body is responsible for lens nourishment, removal of waste products and toning of the eye since the lens does not contain any blood vessels. This internal fluid has low oxygen concentration therefore the lens is made to derive its energy supply mostly from anaerobic metabolism.

The iris is positioned in a suitable place where it can change the shape of the internal lens behind the pupil. The lens in this special place is suspended into position via zonule of zinn ligaments attached to the eye as a ciliary body. The ciliary body contains ciliary muscles where zinn ligaments are attached. Only 0.5 mm of space exists between the lens and the ciliary body. Zinn ligaments are tight when ciliary muscles are resting and this enables a flatter configuration of the lens. Upon contraction of ciliary muscles, zinn ligaments become relaxed and the diameter of the lens decreases along with an increase in its thickness. Thicker lens becomes more globular and this increases its refractive power, thus enabling vision of the closer distances. This increase in refractive power of the lens in order to see closer objects is called “accommodation.” If the stimuli of the ciliary muscles expire, ciliary muscles then relax making zinn ligaments tighter, reducing thickness of the lens, making it flatter and therefore less refractive. This reshapes it to focus on distant objects for a clearer vision.

Accommodation mechanisms and loss of accommodation during aging

The vision blurs temporarily when one takes an immediate shift from staring at an object in the distance to another object nearby. As soon as this blurry image reaches the occipital cortex, stimuli generated here arrives first at the Edinger-Westphal nucleus via special nerve tracks and then to the ciliary muscles of the eye. In a very short time, this blurry vision is corrected and becomes clearer without us even noticing with optimal increase of refraction in the internal lens. In a time as short as 0.35 seconds, for thousands of times in a day, this mechanism is set to function in such a perfect manner to spur those thoughtful minds into reflection and wonder.

Accommodation ability is at its highest point in children and this feature of the eye decreases with age. Refractive power of the lens can increase up to 34 diopters with a 14 diopters accommodation power along with 20 diopters of resting refraction during childhood. This way, children can clearly see objects as close as 7 centimeters. Accommodation power decreases with age. It reduces to 4-8 diopters after the age of 40 and 2-3 diopters around the age of 50. It is widely accepted that refractive power disappears entirely after the age of 60.

In the advanced stages of aging, the eye lens loses its transparency, becomes cloudy as it develops cataract. Eye lens in this poor transparent stage is removed via cataract surgery, to be replaced with an artificial lens to carry out the refracting task. Unfortunately today, technology is still unable to produce an artificial lens that is capable of all the tasks that a human eye can perform. Artificial internal eye lenses that are used in surgeries today cannot carry out accommodation functions. Majority of these lenses can only focus on one point at a near or far distance. Newly developed multifocal lenses can utilize various mechanisms to see both near and far distances yet they are not in any position to replace the human lens completely.

Ocular motions when looking near and far

Thanks to ocular movements, we do not have to move our head constantly while looking around. The eye movement involving both eyes in which each eye moves in the same direction is referred to as version type movements. Another movement type is called vergence, and this is when both eyes move in opposite directions. Vergence type movements are a type of ocular motility coded in a special center part of the brain. It is called convergence because the eyes get closer to each other when looking at closer distances, and called divergence when both eyes focus on the same spot by directing away from each other. If eyes only moved in the same direction without this convergence mechanism, both eyes would not be able to focus on closer points and would not be able to develop three dimensional visions (depth perception).

In addition to accommodation and convergence, when we look closer, our pupils get smaller (Miosis). Light rays coming from outside objects get improved focus on the retina via this constriction of the pupils. This way, a clearer image is provided.

When we look closer, accommodation, convergence and miosis all happen at the same time in a synchronized manner to provide a clear vision. The details of these complicated chains of events have yet to be understood.

Conclusion

The fineness of refractive power of the eye with a single lens, accommodation ability and sensitive balances of ocular motility is only a few of the blessings of the eye granted to humankind. The ability to see near being at its peak during young ages when learning is most active is another dimension to this miracle. These wisdom-filled capacities given to the eye makes one ponder upon the importance of the eye for survival, in addition to being a reminder to those with an open mind and heart to gaze upon the natural world and contemplate upon the Almighty.

Once you realize these things about you and the life that you are living, then it really sounds outrageous when people think they have made a good work of art or they have great taste in art. Could it not be that all people have the same taste but only each individual’s perception is different, as opposed to all people having the same level of perception but different taste?

Most people think that taste is something subjective, that is, everybody has their own taste and that is the end of it. There is nothing more to discuss about taste. Hence, there is no such thing as good taste or bad. Everybody has things they like and things they do not, but no one can say that their taste is any better than someone else’s. Thus, we are all tempted to accept the unquestionable character of taste as the truth since almost everybody agrees on it. Although the majority view is often considered acceptable as a way of ascertaining the truth, there are quite a few examples that show that is just not correct. This article is about one of those examples.

If you are part of the big majority of people that thinks there is no such thing as good taste, you should also think that there is no such thing as good art. I can imagine if I was giving a talk about this article and presenting this exact same argument, there would be fifty hands going up objecting: “That can’t be true; there is Mona Lisa, there is Tortoise Trainer, there is this, and there is that.” But then, whoever did not like Mona Lisa or Tortoise Trainer would just have worse taste than yours, or anybody else who liked it might have better taste for that matter. Hence, we arrive at the conclusion that if there is no good taste, then there is no good art. If we follow the argument further, then there is no good artist.

Suppose you are making a painting or writing a poem, what do you think would be guiding you throughout the whole process? The inevitable answer to this question must be “taste” because each stroke of your brush or each line you add is a decision made by you with the help of your taste. Every move you make is a result of your conscious or subconscious thought that it would make your piece better. But then, if you think that there is no place for a concept of being better in art, you should not be able to make any moves. Not only that, by the same token a brand new blank canvas would be just as good as the ceiling of the Hagia Sophia. What is more, by saving a lot of time and energy, you are doing even better with the blank canvas than the guy who painted the ceiling of Hagia Sophia.

Probably you are thinking that the author of these lines has really lost it now! And maybe, you are thinking that it is about time to move on to the next article. But hold on a second!

I think I may have a solution to this nonsense. If Da Vinci was in Robinson Crusoe’s place, he would still draw the Mona Lisa on that island, but surely, he would be happier if thousands of people came to see it every day. So, there is more to art than pure taste; art has people who appreciate it. It could be argued that an artist enjoys his piece for two possible reasons. First, just because he likes what he does; second, there is an audience who will appreciate what he does.

But before appreciation come attention and interest. People must pay attention or need to have an interest before they understand or even think about something. Only after that do they recognize something is beautiful, and after that comes the appreciation.

Attention and interest are two very broad terms. There are so many different things that attract my attention or interest me, often without me knowing it. Sometimes the rhyme of a poem is so soothing and pleasant that I do not even know, when I read it the first time, that I have actually fallen in love with it. I realize this when I figure out that I have learned the whole thing after a few recitations without expending any special effort to memorize it. It is as if, all of a sudden, I start hearing the constant relaxing whistle of a tall reed in my ears along with the wind. It is a great pleasure to fall asleep in the ambiance of that reed. The bed is no different than a throne for me at that moment.

Once I discover such a lone reed with a soothing melody, I visit her from time to time when I get really tired and need some rest. Then, on one of those visits, just before I fall asleep, I see a ray of a different color through the leaves of the reed; one which I had not noticed before. It is an irreplaceable touch. Surely the poet must have hidden it among the leaves and the branches only for his loyal visitors. Exhilarated by the discovery of this beauty, I start telling the fellows in the shade around me about it. I hear you saying now, “Oh! I thought you were alone under the tree.” No, no! That is impossible. If there is a reed, there will always be fellows under the shade, some for the whistle, some for the colors, some for something you do not know, but there will be always some people enjoying it.

I tell you the little story about me and the poet just to make a point about the type of art that intrigues us. Some art lies in the background quietly, some shakes our very souls and makes us tremble. Some gets carved into our brains immediately, whereas some types challenge our intelligence. In all of those different kinds of good art there is a very essential thing in common. It is the common things that the audience shares.

Although poetry is a type of art with a very broad audience, we can always imagine some people who would have no interest in it at all. Maybe a better example would be a type of beauty that would interest absolutely everybody in this world. Is there anything like that? There are tons of things like that. Who would not like a nightingale singing near dawn, or a warm breeze on the cheek, the harmony of different tones of green in a broad forest, human faces, and the like. Let us focus, for example, on that last one. All of us find human faces interesting, right? I believe that it is encoded in our DNA. A parallel to this is the obsessive compulsion of sculptors to make human faces all the time. Or, think about the number of people whose faces you know but not their names and vice versa. Which number is bigger do you think?

If you are not convinced by these arguments or think that maybe I am biased due to the conditions that I developed in, let us put the same question to babies, who are not biased, at least not just yet! Let us see what they have got to say about this. If you are worried that we cannot really understand what they are saying, there is some help from the psychologists. “In 1961, the psychologist Robert Fantz devised an ingenious method to find out about babies and faces. He designed a stand in which, on the bottom level, the baby lies on his back, looking up. A few feet above is a display area where the experimenter puts two large cards, each containing a design-a white circle, a yellow circle, a bull’s eye, or a simple sketch of face. The researcher, peering down through a tiny peephole, can watch the movement of the baby’s eyes and time how long they are directed at one or the other of each pair of patterns. Fantz found that at two months babies looked twice as long at a bull’s eye as at a circle of solid color, and twice as long at a sketch of a face as at a bull’s eye. Evidently, even a two-month-old can distinguish major differences and direct his gaze toward what he finds more interesting.”¹

With this in mind, we are compelled to acknowledge that the human face appeals to an innate common taste in all humans, either because it is beautiful in itself or because it contains most, if not all, of the things that are to “the common taste” of all humans. Then we can conclude that, as humans, our design is such that we are at least able to appreciate the same things.

Finally, we are in a position to define good art. Good art is such that it passes from its creator and reaches a lot of people who enjoy gazing upon it. Good art attracts attention and interest from a lot of people with different characteristics from different cultures and regardless of all their differences, the essential thing is they all have the same aptitude to enjoy the same thing in various different ways. In other words, good art is a manifestation of unity in multiplicity.

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1. Hunt, M., The Story of Psychology, pp. 366, Anchor Books, 1993