Our language is steeped in visual imagery. In fact, whenever we compare one thing to another, as we constantly do (consider the country expression: “It was raining harder than a cow pissing sideways on a rock”), we are relying on our sense of vision to capture the action or the mood. Seeing is proof positive, we stubbornly insist (“I saw it with my own eyes …”). Of course, in these days of relativity, feats of magic, and tricks of perception, we know better than to trust everything we see (“… a flying saucer landed on the freeway …”). See with our naked eyes, that is. As Dylan Thomas reminds us, there are many “fibs of vision.”* If we extend our eyes by attaching artificial lenses and other accessories to our real ones (glasses, telescopes, cameras, binoculars, scanning electron microscopes, CAT scans, X-rays, magnetic resonance imaging, ultrasound, radioisotope tracers, lasers, DNA sequencers, and so on), we trust the result a little more. But Missouri is still called the Show Me! state, which, as a kind of visual pun, I guess, it displays on its license plates for motorists to see. “The writing is on the wall,” a politician says sagely, forgetting temporarily that it could be a forgery nonetheless. We quickly see through people whose characters are transparent. And, heaven knows, we yearn for enlightenment. “I see where you’re coming from,” one woman says to another in a café, “but you’d better watch out, he’s bound to see what you’re up to.” See for yourself! the impatient exclaim to disbelievers. After the Bible’s first imperative—“Let there be light”—God viewed each day’s toil and “saw that it was good.” Presumably, He, too, had to see it to believe it. Ideas dawn on us, if we’re bright enough, not dim-witted, especially if we’re visionary. And, when we flirt, though the common phrase sounds quite ghoulish and extreme, we give someone the eye.
The process of seeing began very simply. In the ancient seas, life-forms developed faint patches of skin that were sensitive to light. They could then tell light from dark, and also the direction of the light source, but that was all. These skills turned out to be so useful that eyes evolved that could judge motion, then form, and finally a dazzling array of details and colors. One reminder of our oceanic origins is that our eyes must be constantly bathed in salt water. Some of the oldest eyes on record are those of the trilobite, one of the great success stories of the Cambrian age, which we now know only through its plentiful fossil remains. As I type this, I am wearing on a chain around my neck a small trilobite fossil, set in a silver bezel. Five hundred million years ago, it thrived in the swamps, with compound faceted eyes that could see mainly sideways but, unfortunately, not up. On the other hand, the newest eyes are those we have invented, such as the electric eye (based on what we learned about the motion-detecting design of the frog’s eye), or the mirror telescope (based on the contrast-judging design of the horseshoe crab’s eye), or synchronous lenses for use in microsurgery, optical scanning, and severe vision problems (based on the double lens of copilia, a myopic crustacean that lives deep in the Mediterranean). Although plants do not have eyes, Loren Eiseley argues eloquently for the eye of the fungus pilobolus, which has a light-sensitive area that controls the spore cannon it aims at the brightest spot it can find.
We think of our eyes as wise seers, but all the eye does is gather light. Let’s consider the light-harvesting. As we know, the eye works a lot like a camera; or rather, we invented cameras that work like our eyes. To focus a camera, you move the lens closer to or farther away from an object. The eye’s rubbery, bean-shaped crystalline lens achieves the same result by changing its shape—the lens thins to focus on a distant object, which looks small; thickens to focus on a near one, which looks large. A camera can control the amount of light it allows in. The iris of the eye, which is really a muscle, changes the size of a small hole, the pupil,* through which the light enters the eyeball. Because fish don’t have this pupillary response, in which the iris protects against sudden surges of light, and most of them do not have eyelids (since their eyes are constantly bathed in water), they’re much more susceptible to dazzlement than we are. In addition to its gate-keeping function, the iris, named after the Greek word for rainbow, is what gives our eyes their color. Caucasian eyes appear blue at birth, Negro eyes brown. After death, Caucasian eyes appear greenish-brown. Blue eyes are not inherently blue, not stained blue like fabric: They appear blue because they have less pigment than brown eyes. When light enters “blue” eyes, the very short blue light rays scatter as they jump off tiny, nonpigmented particles; what we see are the scattered rays, and the eyes appear to be blue. Dark eyes have densely packed pigment molecules and absorb the blue wavelengths, at the same time reflecting other colors whose rays are longer. They therefore appear to be brown or hazel. Though on casual inspection irises may look pretty much the same, the pattern of color, starbursts, spots, and other features is so highly individual that law-enforcement people have considered using iris patterns in addition to fingerprints.
At the back of a camera, film records the images. Lining the rear wall of the eyeball is a thin sheet, the retina, which includes two sorts of photosensitive cells, rods and cones. We need two because we live in the two worlds of darkness and light. A hundred and twenty-five million thin, straight rods construe the dimness, and report in black and white. Seven million plump cones examine the bright, color-packed day. There are three kinds of cones, specializing in blue, red, and green. Mixed together, the rods and cones allow the eye to respond quickly to a changing scene. One place on the retina, where the optic nerve enters the brain, has no rods or cones at all and, as a result, does not perceive light; we refer to it as our “blind spot.” But right in the middle of the retina lies a small crater, the fovea, filled with highly concentrated cones, which we use for precision focusing when we want to examine an object in bright light, to drag it into sharp view and grip it with our eyes. Because the fovea is so small, it can perform its magic only on a small area (a four-inch-square snapshot at eight feet, for example). Almost every cone in a fovea has its own direct line to higher centers in the brain; elsewhere on the retina, rods and cones may serve many cells, and vision is vaguer. The eyeball moves subtly, continuously, to keep an object in front of the fovea. In dim light, the fovea’s cones are almost useless; instead we must look just “off” of an object to see it clearly with the surrounding rods, not directly at it because the fovea would fail us and the object appear invisible. Because the rods see no color, we don’t perceive color at night. When the retina observes something, neurons pass the word along to the brain through a series of electrochemical handshakes. In about a tenth of a second, the message reaches the visual cortex, which begins to make sense of it.
However, seeing, as we think of it, doesn’t happen in the eyes but in the brain. In one way, to see flamboyantly, in detail, we don’t need the eyes at all. We often remember scenes from days or even years earlier, viewing them in our mind’s eye, and can even picture completely imaginary events, if we wish. We see in surprising detail when we dream. Sometimes when I’m in a visually besotting landscape, somewhere out in nature and experiencing intense rapture, I lie down at night and close my eyes, and see the landscape parading across the inside of my closed lids. The first time this happened—on a 200,000-acre working cattle ranch, surrounded by pastel mesas, in the New Mexico desert—I was a little spooked. Wrung out from the rigors of the branding corral, I needed sleep, but all the day’s images, gestures, and motions still blazed in my visual memory. It was not like dreaming: it was like trying to sleep with your eyes wide open during a fiesta in full swing.
The same thing happened more recently, this time in Antarctica. One sunny day, we cruised through Gerlache Strait, which narrows to 1600 feet at its southern end; ice mountains towered on either side of the ship. Black jagged mountains, covered in cascading snow and ice, looked like penguins standing in familiar postures in a wash of brilliant light. While real penguins porpoised beside the boat, huge icebergs floated by, with bases of pale blue and sides of mint green. In the ship’s glassed-in observation deck, people s
at in armchairs at the window, some dozing. One man held out his pinky and first finger as if giving someone the evil eye, but he was measuring an iceberg. Deception Island, though distant, looked close and clear in the sterile air. A crib of ice holding a soft blue wash in its palms drifted close to the ship. Across the strait, ice calved off a glacier with a loud explosive crumble. Pastel icebergs roamed around us, some tens of thousands of years old. Great pressure can push the air bubbles out of the ice and compact it. Free of air bubbles, it reflects light differently, as blue. The waters shivered with the gooseflesh of small ice shards. Some icebergs glowed like dull peppermint in the sun—impurities trapped in the ice (phytoplankton and algae) tinted them green. Ethereal snow petrels flew around the peaks of the icebergs, while the sun shone through their translucent wings. White, silent, the birds seemed to be pieces of ice flying with purpose and grace. As they passed in front of an ice floe, they became invisible. Glare transformed the landscape with such force that it seemed like a pure color. When we went out in the inflatable motorized rafts called Zodiacs to tour the iceberg orchards, I grabbed a piece of glacial ice and held it to my ear, listening to the bubbles cracking and popping as the air trapped inside escaped. And that night, though exhausted from the day’s spectacles and doings, I lay in my narrow bunk, awake with my eyes closed, while sunstruck icebergs drifted across the insides of my lids, and the Antarctic peninsula revealed itself slowly, mile by mile, in the small theater of my closed eyes.
Because the eye loves novelty and can get used to almost any scene, even one of horror, much of life can drift into the vague background of our attention. How easy it is to overlook the furry yellow comb inside the throat of an iris, or the tiny fangs of a staple, or the red forked tongue of a garter snake, or the way intense sorrow makes people bend their bodies as if they were blowing in a high wind. Both science and art have a habit of waking us up, turning on all the lights, grabbing us by the collar and saying Would you please pay attention! You wouldn’t think something as complexly busy as life would be so easy to overlook. But, like supreme racehorses, full of vitality, determination, and heart, we tend to miss sights not directly in our path—the colorful crowds of people on either side, the shapes left in the thickly rutted track, and the permanent spectacle of the sky, that ever-present, ever-changing pageant overhead.
HOW TO WATCH THE SKY
I am sitting at the edge of the continent, at Point Reyes National Seashore, the peninsula north of San Francisco, where the land gives way to the thrall of the Pacific and the arching blue conundrum of the sky. When cricket-whine, loud as a buzz saw, abruptly quits, only bird calls map the quiet codes of daylight. A hawk leans into nothingness, peeling a layer of flight from thin air. At first it flaps hard to gain a little altitude, then finds a warm updraft and cups the air with its wings, spiraling up in tight circles as it eyes the ground below for rodents or rabbits. Banking a little wider, it turns slowly, a twirling parasol. The hawk knows instinctively that it will not fall. The sky is the one visual constant in all our lives, a complex backdrop to our every venture, thought, and emotion. Yet we tend to think of it as invisible—an absence, not a substance. Though we move through air’s glassy fathoms, we rarely picture it as the thick heavy arena it is. We rarely wonder about the blue phantasm we call the sky. “Skeu,” I say out loud, the word that our ancient ancestors used; I try to utter it as they might have, with fear and wonder: “Skeu.” Actually, it was their word for a covering of any sort. To them, the sky was a roof of changing colors. Small wonder they billeted their gods there, like so many quarrelsome neighbors who, in fits of temper, hurled lightning bolts instead of crockery.
Look at your feet. You are standing in the sky. When we think of the sky, we tend to look up, but the sky actually begins at the earth. We walk through it, yell into it, rake leaves, wash the dog, and drive cars in it. We breathe it deep within us. With every breath, we inhale millions of molecules of sky, heat them briefly, and then exhale them back into the world. At this moment, you are breathing some of the same molecules once breathed by Leonardo da Vinci, William Shakespeare, Anne Bradstreet, or Colette. Inhale deeply. Think of The Tempest. Air works the bellows of our lungs, and it powers our cells. We say “light as air,” but there is nothing lightweight about our atmosphere, which weighs 5,000 trillion tons. Only a clench as stubborn as gravity’s could hold it to the earth; otherwise it would simply float away and seep into the cornerless expanse of space.
Without thinking, we often speak of “an empty sky.” But the sky is never empty. In a mere ounce of air, there are 1,000 billion trillion gyrating atoms made up of oxygen, nitrogen, and hydrogen, each a menagerie of electrons, quarks, and ghostly neutrinos. Sometimes we marvel at how “calm” the day is, or how “still” the night. Yet there is no stillness in the sky, or anywhere else where life and matter meet. The air is always vibrant and aglow, full of volatile gases, staggering spores, dust, viruses, fungi, and animals, all stirred by a skirling and relentless wind. There are active flyers like butterflies, birds, bats, and insects, who ply the air roads; and there are passive flyers like autumn leaves, pollen, or milkweed pods, which just float. Beginning at the earth and stretching up in all directions, the sky is the thick, twitching realm in which we live. When we say that our distant ancestors crawled out onto the land, we forget to add that they really moved from one ocean to another, from the upper fathoms of water to the deepest fathoms of air.
The prevailing winds here are from the west, as I can see from the weird and wonderful shapes of the vegetation along the beach. A light steady breeze blowing off the Pacific has swept back the wild grasses into a sort of pompadour. A little farther back, in a more protected glade, I find a small clump of them, around which a circle runs in the dirt. It looks as if someone pressed a cookie cutter down in the ground, but the wind alone has done it, blowing the grass around and turning it into a natural protractor. We think of the wind as a destructive force—a sudden funnel that pops a roof off a schoolhouse in Oklahoma—but the wind is also a gradual and powerful mason that carves cliffs, erodes hillsides, re-creates beaches, moves trees and rocks down mountains or across rivers. Wind creates waves, as in the sensuously rippling dunes of Death Valley or along the changing shorelines. The wind hauls away the topsoil as if it were nothing more than a dingy tablecloth on the checkerboard fields of the Midwest, creating a “dust bowl.” It can power generators, gliders, windmills, kites, sailboats. It sows seeds and pollen. It sculpts the landscape. Along rugged coasts, one often sees trees dramatically carved by the relentless wind.
The north wind is shown on ancient maps as a plump-cheeked man with tousled hair and a strained expression, blowing as hard as he can. According to Homer, the god Aeolus lived in a palatial cave, where he kept the winds tied up in a leather bag. He gave the bag to Odysseus to power his ship, but when Odysseus’s comrades opened the bag the winds raced free throughout the world, squabbling and whirling and generally wreaking havoc. “The children of morning,” Hesiod called the Greek winds. To the ancient Chinese, fung meant both wind and breath, and there were many words for the wind’s temperaments. Tiu meant “to move with the wind like a tree.” Yao was the word for when something floated on the breeze like down. The names of winds are magical, and tell a lot about the many moods the sky can take. There’s Portugal’s hillside vento coado; Japan’s demonic tsumuji, or soft pine-grove-loving matsukaze;
Australia’s balmy brickfielder (which first described dust storms blowing off brickyards near Sydney); America’s moist warm chinook drifting in from the sea, and named after the language of Indians who settled Oregon; or snow-clotted blizzard, or fierce Santa Ana, or Hawaii’s humid waimea; North Africa’s hot, sand-laden desert simoom (from the Aramaic word samma, “poison”); Argentina’s baking, depleting zonda, which pours down from the Andes to sweep the pampas; the Nile’s dark, gloomy haboob; Russia’s gale-force buran, bringing a storm in the summer or a blizzard in the winter; Greece’s refreshing summer etesian; Switzerlan
d’s warm, gusty foehn blowing off the leeward slopes of a mountain; France’s dry cold mistral (“master wind”) squalling through the Rhône Valley and down to the Mediterranean coast; India’s notorious monsoon, whose very name means a whole season of monsoons; the Cape of Good Hope’s bull’s-eye squall; Alaska’s petulent williwaw; Gibraltar’s easterly-blowing datoo; Spain’s mellifluous solano; the Caribbean’s hurricane (derived from the Taino word huracan, which means “evil spirit”); Sweden’s gale-level frisk vind; China’s whispering I tien tien fung, or first autumn breeze, the sz.
Storms have been fretting the coast here for days, and now thick gray clouds stagger across this sky. I watch mashed-potato heaps of cumulus (a word that means “pile”) and broad bands of stratus (which means “stretched out”). As author James Trefil once observed, a cloud is a sort of floating lake. When rising warm air collides with descending cold air, the water falls, as it does now. I take shelter on a porch, while a real toad-strangler starts, a full-blooded, hell-for-leather thunderstorm, during which the sky crackles and throbs. Lightning appears to plunge out of it, a pitchfork stabbing into the ground. In fact, it sends down a short electrical scout first, and the earth replies by arcing a long bolt up toward the sky, heating the air so fast that it explodes into a shock wave, or thunder, as we call it. Counting the seconds between a lightning flash and the thunder, I then divide by five, and get a rough idea of how far away it is—seven miles. In one second, sound travels 1,100 feet. If the lightning flash and the thunder arrive at the same time, one doesn’t have much of a chance to count. In a little while the storm quiets, as the thunder bumpers roll farther up the coast. But some clouds still stalk the sky. A cloud rhinoceros metamorphoses into a profile of Eleanor Roosevelt; then a bowl of pumpkins; then a tongue-wagging dragon. Parading hugely across the sky, clouds like these have squatted above people of all times and countries. How many vacant afternoons people have passed watching the clouds drift by. The ancient Chinese amused themselves by finding shapes in the clouds just as Inuits, Bantus, and Pittsburghers do now. Sailors, generals, farmers, ranchers, and others have always consulted the crystal ball of the sky to foretell the weather (lens-shaped clouds—severe winds aloft; dappled or “mackerel” sky—rain is near; low, thick, dark, blanketlike clouds—a stormy cold front may be coming), devising jingles, maxims, and elaborate cloud charts and atlases, graphics as beautiful as they are useful. On a train through Siberia, Laurens van der Post looked out the window at the huge expanse of flat country and endless sky. “I thought I had never been to any place with so much sky and space around it,” he writes in Journey into Russia, and was especially startled by “the immense thunder clouds moving out of the dark towards the sleeping city resembling, in the spasmodic lightning, fabulous swans beating towards us on hissing wings of fire.” As van der Post watched the lightning from the train, the Russian friend accompanying him explained that they had a special word in his language for just that scene: Zarnitsa.
A Natural History of the Senses Page 27