The courtyard of the Museo n.a.z.ionale looked a little like courtyards at the University of Cambridge. "We don't have so many fragments there," said Aubrey. "Then again, our things are only about one-third as old."

Ravenna was the capital of the Western Roman Empire. It was also the capital of the Kingdom of the Ostrogoths.

And when the Byzantine emperor Justinian retook a piece of the boot of Italy, he kept Ravenna as his capital. As a port on the Adriatic Sea, it was a convenient place from which to sail to Byzantium. During Justinian's reign many of the famous mosaics were made, enclosed in plain brick churches, like souls inside bodies. Yeats called the mosaics "monuments of unaging intellect" in his great late poem "Sailing to Byzantium."

"You realize that if ages stretch as you predict, then these antiquities become meaningless," I said.

"That is my ambition," said Aubrey. "I look forward to that." He discreetly checked his watch.

Aubrey and I wandered, to his growing disgust, through the churches of Ravenna. In the Tomb of Galla Placidia, stags (representing souls) drank from a mystic fountain encircled by curlicues of greenery, as if all life had turned into music. Dante's heart would have been touched by these scenes as he finished his Divine Comedy Divine Comedy, in exile from Florence, during the last four years of his life. His epitaph concludes: "Here I lie buried, Dante, exile from my birthplace, a son of Florence, that loveless mother."

At the Basilica of San Vitale I pointed out the peac.o.c.ks that face each other on a stone sarcophagus. There were rows of them, symbols of immortality, waiting for resurrection. And then there were still more symbols of eternity and immortality: mosaic birds at a mosaic fountain. The church was built when the Goths were still in Rome. Among the pillars and the groin vaults of the chancel, the Lamb of G.o.d was framed in a wreath against a night sky full of gold and silver stars.

"Well, they're fixated, really, in this place, aren't they," said Aubrey, with a donnish drawl. "Can't imagine why why." That killing drawl-that slight rasp of the blade. I asked him if he'd learned it in college.

"It's sort of more Harrow than Cambridge," Aubrey said.

"It's like the drop shot in tennis," I said.

"A part of my national heritage."

While I admired San Vitale, he settled himself in a pew to wait for me. A chair fell over somewhere in the church with an echoing crash. Then the organ began with a portentous chord, another crash. Aubrey glanced at me with an eyebrow drolly c.o.c.ked. The chords of the organ went rolling like the waves that washed the marbles smooth-groaning and building toward some great convulsion to which fewer and fewer would aspire. Aubrey had bowed his head as if in prayer. When I offered him a penny for his thoughts, he said he was hatching plans to raise the circulation rate of his journal, Rejuvenation Research Rejuvenation Research.

As we walked on from church to church through the streets of Ravenna, facing into our own lengthening shadows, Aubrey diverted himself by wrapping up the riddles of the day. In Wonderland, the Mad Hatter asks Alice a riddle without an answer. "Why is a raven like a writing-desk?" But in Aubrey's world, puzzles are made to be answered, and I should answer the questions he'd put to me that morning: How many three-letter words for parts of the human body? (Answer: nine-arm, leg, eye, ear, jaw, gut, toe, lip, and hip.) Now, in the sinking sun, the failing light, he just wanted to go home.

I'd hoped to find Dante's tomb before we left, but Aubrey was getting very tired and sulky. "Maybe, I think, we've seen it," he said. "They all look the same after a while."

Our last stop was the Baptistery of the Arians ("sometimes called the Neonian Baptistery in honor of Bishop Neon who had it decorated during the middle of the fifth century"). Aubrey remembered it vaguely-he'd stayed next to it. According to my guidebook, it was probably an old Roman bath. The Nymphaeum was decorated with mosaics at the order of Bishop Neon sometime after 452. Directly above, on the ceiling, Jesus was baptized in the Jordan, with a dove descending. Aubrey took a chair with a little groan of pleasure and a smothered yawn. The other tourists around us craned their heads up, and he let his own head fall back, too.

The ceiling was said to have inspired Dante's vision of Paradise. Jesus Christ is baptized at the very top of the dome, in the medallion in the center. All the mosaics and the architectural elements are arranged beautifully to lift your eyes toward that central medallion. The dome is circular. The interior includes apses, arches, columns, windows, niches, porticoes, spandrels, mosaics of thrones and altars. The spandrels are decorated with mosaics of the Prophets and tendrils of acanthus. In the scene within the medallion, against a background of gold, there is a rocky riverbank with radiant flowers, the blue water of the Jordan. A river G.o.d holds a green towel to dry off Jesus. The river G.o.d has green hair and beard, and a green staff, along with the green beach towel.

High up in the dome, Saint Peter and Saint Paul lead the Apostles, dressed in gold and silver tunics, in solemn procession. They seem to go around and around like one of the "eternal wheels" that Dante saw in the dome of heaven, and the medallion seems to spin like a cosmic pinwheel.

Below the medallion, in his chair, Aubrey looked almost martyred. His face was pale. His cheeks were hollow. His beard hung a good distance down his chest. It was a better beard than John the Baptist's; longer than the beards of the Apostles; much longer than the beard of the young Moses on his hike up Mount Sinai, where he pauses to relace his sandal.

Well, why would Aubrey be moved by any of these saints and sages in their holy fire? Aubrey has his own hopes. We are hurtling toward a sort of technological supernova, an intelligence explosion, a Singularity. The Singularity will bring a golden age. Not long ago, he wrote an online paean to the Singularity in which he concluded, "Humanity will at that point be in a state of complete satisfaction with its condition: complete ident.i.ty with its deepest goals. Human nature will at last be revealed."

To Aubrey, the failure of our collective will, of our human nerve, is the greatest obstacle to the achievement of escape velocity. Our blindness to what we can be is what prevents us from moving toward the Singularity. We are the weakest link.

The pilgrims and tourists in the church made their way around him where he sat. They glanced at him, at his pallor and hollow cheeks, and they averted their eyes as if here must be a man who was more serious about immortality than they.

The swirling gold world in the mosaics around them suggested grace, and chaotic snake rings of gold against the black-grace unfolding against the blackness of s.p.a.ce or the intense inanity of nothingness, not-being. In his weariness, Aubrey looked like one of the saints or hermits come to life-with no time or patience whatever for the world he had just come out of, interested only in the world to which he was going, or hoped to go, the route to the next world. The past held no interest for him, and the present world interested him only as a portal to the next. In that way, at least, he was not unlike the saints and martyrs who regard him just as stiffly from above-returning the gaze of oblivion.

There Aubrey sat with his martyred look, dark, hollow-eyed, and grave-the mark of thought on the pallor of the face. Under the great mosaic dome of the Battistero Neoniano, his head was thrown way back. His eyes were closed, his hands folded.

The pilgrims and tourists tried not to stare at him.

A baby in a stroller gazed at the beard, solemnly fascinated. The parents politely hurried the stroller on by.

But Aubrey David Nicholas Jasper de Grey was fast asleep.

PART III.

THE GOOD LIFE.

So teach us to number our days, That we may apply our hearts unto wisdom.

-PSALM 90

Chapter 10.

LONG FOR THIS WORLD.

Mortality is at our core. We are long for this world, compared with life in the microcosm of the paramecium, the bacterium, or the Tokophrya Tokophrya standing on the pillar of its holdfast. We have a greater portion of time than most of the other living things with which we share this planet. And yet how we long for this world, how we wish we had more years to explore and enjoy it! How sharply we feel, at every moment of our lives, that mortality is deeply ingrained within us! standing on the pillar of its holdfast. We have a greater portion of time than most of the other living things with which we share this planet. And yet how we long for this world, how we wish we had more years to explore and enjoy it! How sharply we feel, at every moment of our lives, that mortality is deeply ingrained within us!

"To be a philosopher is to learn how to die," said Montaigne. But as a thinker during the Renaissance, he didn't have much time to learn to do it. He wrote in his tower, in his final essay, "Experience,"

"I have recently pa.s.sed six years beyond the age of fifty, which some nations, not without cause, have prescribed as such a proper limit of life that they allowed no one to exceed it. Yet I still have flashes of recovery."

I'm glad we live at a time when a writer who has just turned fifty-six is not all that old. (Flashes of decrepitude here, but still young enough to go forward, I hope.) "Write as if you were dying," Annie Dillard advises in her book The Writing Life The Writing Life. "At the same time, a.s.sume you write for an audience consisting solely of terminal patients. That is, after all, the case."

And that has always been the case, although now we live in a moment when, as we philosophize and grope toward wisdom, we can wonder just what and how different the term and the sentence may be, and if, and when, and what then.

From the beginning our philosophers have tried to teach us how to die, and our poets have taught us that to contemplate death is to learn how to live. Seneca wrote, "We must make ready for death before we make ready for life." "You have noticed that everything an Indian does is in a circle, and that is because the Power of the World always works in circles, and everything tries to be round," said Black Elk, the Oglala Sioux holy man. "The sky is round, and I have heard that the earth is round like a ball, and so are all the stars. The wind, in its greatest power, whirls; birds make their nests in circles, for theirs is the same religion as ours.... Even the seasons form a great circle in their changing, and always come back again to where they were. The life of a man is a circle from childhood to childhood, and so it is in everything where power moves." Walt Whitman ends his poem "Out of the Cradle Endlessly Rocking" with a paean to "death, death, death, death."

I once met Aubrey and Adelaide at the Eagle with my family; he'd offered to take us punting on the Cam. But it rained that day, and we ducked into the Fitzwilliam Museum instead. The gla.s.s displays in the museum included one of Isaac Newton's notebooks and a few of Charles Darwin's letters. Aubrey strode through the halls of treasures at the same clip and with the same degree of interest with which he'd hurried through Ravenna. He was trying, as always, to recruit my boys to his cause. At one point I stopped at a gla.s.s case to read the ma.n.u.script of John Keats's "Ode to a Nightingale," which the poet wrote one morning on Hampstead Heath, a short walk from the house where we were staying in London.

I have been half in love with easeful death....

Keats had a year and some months to live when he wrote that line, at the age of twenty-three. He had already lost his brother Tom to tuberculosis, and caught the disease himself. While I leaned over the gla.s.s museum case, one of my sons squatted on the floor with his back against the wall, and Aubrey settled down right next to him, urgently explaining his own plans for the engineering of thousand-year lives.

From the first age to our own, mortality has been the theme of writers, including the writers who loomed like immortals to my generation, the giants whose very names can still make us feel as small and hopeless as epigones, even though they are all going now or gone, after all that jockeying for immortality. Norman Mailer wrote about WASPS: "They had divorced themselves from odor in order to dominate time, and thereby see if they were able to deliver themselves from death." Saul Bellow took John Cheever to the Russian baths in Chicago. "Wreathed in vapor he looked more immortal than I," Cheever reported in a letter to his brother, "but I think he was trying." "G.o.d save us from ever ending, though billions have," John Updike wrote in his last cycle of poems, Endpoint Endpoint, when he was dying of cancer at Ma.s.sachusetts General Hospital.

Mortality, impermanence, ephemerality: this has been the great theme of modern science, too. Galileo's discovery of sunspots ran counter to traditional astronomy and its view of the sun as immortal. People had always thought the sun was perfect, eternal, and spotless; he argued that the sun could be mortal and decay-like the rest of us. "It proves nothing to say...that it is unbelievable for the dark spots to exist in the sun because the sun is a most lucid body," Galileo wrote impatiently. "So long as men were in fact obliged to call the sun 'most pure and most lucid,' no shadows or impurities whatever had been perceived in it; but now it shows itself to us as partly impure and spotty, why should we not call it 'spotted and not pure'? For names and attributes must be accommodated to the essence of things, and not the essence to the names, since things come first and names afterwards."

Galileo saw ruin not only in the sun but also in the moon, when he pointed his telescope there. And he much preferred a cosmos in motion and even in decay to a cosmos that, once created, never changed: I cannot hear it to be attributed to natural bodies, for a great honour and perfection that they are impa.s.sible, immutable, inalterable, &c.... It is my opinion that the Earth is very n.o.ble and admirable, by reason of so many and so different alterations, mutations, generations, &c. which are incessantly made therein; and if without being subject to any alteration, it had been all one vast heap of sand, or a ma.s.se of Jasper...wherein nothing had ever grown, altered, or changed, I should have esteemed it a lump of no benefit to the World, full of idlenesse, and in a word superfluous, and as if it had never been in nature; and should make the same difference in it, as between a living and a dead creature: The like I say of the Moon, Jupiter, and all other Globes of the World.

And this has been the drift of science ever since, in the discovery of the deep geological layers of the earth, and the vast numbers of species that have gone extinct, to be preserved only within those layers; and in the lives and deaths of the stars; and in the cycle of the life and death of the universe itself-all of which those sunspots prefigured.

If anything, the cosmos of science is as ephemeral as the cosmos of Buddha, who founded a religion on evanescence, as on a rock. Siddh[image]rtha Gautama, who became the Buddha, wearying when very young of the sights and dread of mortality, shocked by his first sight of an old man by the side of the road, left Lumbini on a pilgrimage into the mountains: "Grieve not for me," he said, "but mourn for those who stay behind, bound by longings to which the fruit is sorrow...for what confidence have we in life when death is ever at hand?...Even were I to return to my kindred by reason of affection, yet we should be divided in the end by death. The meeting and parting of living things is as when clouds having come together drift apart again, or as when the leaves are parted from the trees. There is nothing we may call our own in a union that is but a dream."

Mortality is the central fact of our lives. Contrary to rumor, we do know it even when we are young. We are adept at pushing the thought away, but it is there with us almost from the beginning. There are times in every life when we find it hard to think about and impossible to withdraw from. We try to number our days, so that we may apply our hearts unto wisdom, as we are advised in the Psalms. And it is essential to us at any age to know or to guess roughly where we are in our time-because that knowledge does teach us how to live. Laura L. Carstensen, a psychologist at Stanford, has presented an interesting paper in Science Science, "The Influence of a Sense of Time on Human Development." When we have reason to believe that we have decades ahead of us-our whole life ahead of us, as we say-we focus our energies on adventures, new experiences, learning new things: the advancement of learning. When we believe that we have very little time left, we focus more on experiences that have emotional meaning for us; the meaning we have found and made.

For Carstensen and her colleagues, this helps make sense of what psychologists have sometimes called the "paradox of aging." Older people tend to want to spend their time within a small social circle of a few close friends and loved ones. They want to focus their time and energy where they have already found their greatest satisfaction. And though their world is smaller, they often say they are as happy as young people, if not happier.

Ask old people how they want to spend time, and almost always that is what they say: they want to spend it with their loved ones. Young people asked the same questions will choose to spend time on new experiences. In one test, Carstensen showed people a travel poster with the usual spread of photographs: a cheetah, a parrot, a family picnicking on a trip, the Sphinx. One poster carried the message, "Capture those special moments." The other poster read, "Capture the unexplored world." The old people in the study chose to capture those special moments; the young people were more attracted to the unexplored world. "Young or old, when people perceive time as finite," Carstensen writes, "they attach greater importance to finding emotional meaning and satisfaction from life and invest fewer resources into gathering information and expanding horizons." And when we see time as virtually infinite, our priorities reverse.

In one experiment, Carstensen and her colleagues asked their subjects to imagine that their doctor had just called to say that science had made a medical breakthrough, which would give them many more years to live. Now they were willing and eager to spend time with new people and broaden their horizons. But if they were asked to imagine that they would soon leave their homes and move somewhere very far away, most of them said that they would spend their remaining time with a few of the people they were closest to. Young and old had the same reaction. What mattered here was not how old they were, how much time they'd lived, but how much time they thought they had ahead. Carstensen writes, "Preferences long thought to reflect intractable effects of biological or psychological aging appear fluid and malleable."

When we're in the first few ages of man, the last few ages seem very far away. But we do know those last ages are there, and death is there. And it is healthy and adaptive to know that; to number our days, that we may try to be wise; even if we are adept a moment later at pushing the thought away.

When we arrive at the late ages we are still consumed with the problem of mortality and still adept at pushing it away. In fact, when we're old (having arrived at that state as if suddenly), mortality means so much to us that it might crowd out everything else, if we weren't so good at thinking about it and then trying to ignore it again. An old New Yorker New Yorker cartoon shows a man of a certain age reading the obituaries and thinking: cartoon shows a man of a certain age reading the obituaries and thinking: Twelve years older than me.... Five years older than me.... My G.o.d, exactly my age... Twelve years older than me.... Five years older than me.... My G.o.d, exactly my age.... People have computed that way since the days of the first newspapers, sometimes with a frisson of fear, but often with a strange feeling of comfort afterward. As Dr. Johnson observes, "The computer refers none of his calculations to his own tenure, but persists, in contempt of probability, to foretell old age to himself, and believes that he is marked out to reach the utmost verge of human existence, and see thousands and ten thousands fall into the grave."

From beginning to end it is this knowledge of the limit, the endpoint, death, that looms largest in our calculations and our struggles, and touches us most deeply in the stories of the struggles of our heroes. At the Eagle, patrons often wander under the blood-red ceiling of the RAF Room and read the initials of the pilots, the nicknames of their squadrons and commanders. "Donald Jimmie Moore." "Bert's Boys." "The Pressure Boys." You can make out the form of a woman who floats across the ceiling like a constellation. She is remembered in the pub as Ethel. She may have been the land-lady's sister. Apparently the young airmen lifted her up to the ceiling one night and drew her outline in lipstick, and apparently she had lost her clothes.

The young airmen wrote up there with their lighters, with that lipstick, with candles, and with charcoal from the fireplace.

"Alis Nocturnes," a motto: "On the Wings of the Night." a motto: "On the Wings of the Night."

"58." The Fifty-eighth squadron was commanded by Sir Arthur Travers Harris, known as "Bomber" Harris to the press and as "Butcher" Harris to his men. The men were as young as seventeen, but they knew. The Fifty-eighth squadron was commanded by Sir Arthur Travers Harris, known as "Bomber" Harris to the press and as "Butcher" Harris to his men. The men were as young as seventeen, but they knew.

In what is now the Eagle's DNA Room, James Watson was oppressed by a sense of his own mortality. Watson was convinced that great scientists achieve breakthroughs by the age of twenty-five, and he barely made it. Soon after his eureka moment with Crick, and their victory lunch, Watson made his way to Paris, where he did not have much luck finding girls, in spite of his bohemian long hair and sneakers. He ends The Double Helix The Double Helix on a melancholy note, staring at the girls near Saint-Germain-des-Pres: "I was twenty-five and too old to be unusual." on a melancholy note, staring at the girls near Saint-Germain-des-Pres: "I was twenty-five and too old to be unusual."

Among the innumerable things it does to us, mortality binds us in mutual piety, when we're young, like those pilots. The problem of mortality pushes us to choose a path; it goads us to accomplish something, like Watson and Crick. We push it away with all of the missions that fill the first ages of man, but we know the problem is there, and it goads us to ask the largest questions-questions of ultimate meaning; questions we might never think to ask if we had all the time in the world.

This problem of mortality will define our next years and decades. It will involve not only writers, philosophers, and biologists but also sociologists, economists, and politicians. It will weigh on our minds at least as much as at any time in history, with or without the discovery of an elixir of youth. Because of our success on the planet, we face a new era even without the elixir.

"Very long lives are not the distant privilege of remote future generations," according to an a.n.a.lysis by the Danish gerontologist Kaare Christensen and colleagues; "very long lives are the probable destiny of most people alive now in developed countries." Life expectancy has been rising on a straight line for more than 165 years. This linear progress "does not suggest a looming limit to human life span," they argue. "If life expectancy were approaching a limit, some deceleration of progress would probably occur. Continued progress in the longest-living populations suggests that we are not close to a limit, and further rise in life expectancy seems likely."

Life expectancy has doubled over the past two hundred years, and in the last half century most of that rise came from improvements in the lives of the old, whereas before, it had come from improvements for the young. The number of centenarians on the planet has more or less doubled with every decade since 1960. At the moment, j.a.pan is the country that offers the most years of life to its citizens. In 1950 a woman in j.a.pan who had just reached age 65 could expect to live another thirteen years. Fifty years later, a j.a.panese woman who reached age 65 could expect another twenty-two years. In 1950, her chance of reaching age 100 was less than one in a thousand. By 2002, her chance was one in twenty.

According to Christensen, the elderly in Denmark are living longer without spending more years sick, frail, and in pain. A recent study followed more than two thousand elderly Danes. Between ages 92 and 100, the number of those who could live independently, shopping, cooking, and bathing, declined only slightly, from 39 percent to 33 percent. Even at age 100, one in three Danes was still independent. That's pleasant news for warm, fallible human computers of a certain age (although it's not quite as comforting as it sounds, because most of those 92-year-olds never made it to 100).

These forecasts could be wrong. The long rise in life expectancy through history has been broken here and there, chipped into jagged and serrated edges like a flint knife, interrupted by the great wars, famines, and epidemics. In the fourteenth century the Great Plague killed nearly half the population of Europe. Baby boomers have to look only one generation back to remember the global cataclysm that brought them into the world. More than 50 million people died in World War Two. Russian men died in such numbers during the war that there was a shortage of able-bodied males in the Soviet Union for a whole generation. Lately the life expectancy of Russian men has been declining again, because of too little work, too little food and medicine, and too much vodka and tobacco.

S. Jay Olshansky, a well-respected demographer at the School of Public Health at the University of Illinois in Chicago, thinks we're already at the limit of human life expectancy. He believes that we are not likely to extend it beyond about eighty-five years. He warns that in the United States, average life expectancy may soon begin to decline, as in Russia, because of too many burgers and fries.

More optimistic demographers point out that Olshansky has been wrong before. In 1990, he predicted that life expectancy at age fifty would not exceed thirty-five years "unless major breakthroughs occur in controlling the fundamental rate of aging." As things turned out, j.a.panese women were already exceeding this life expectancy by 1996.

The implications of these changes for the world's economies are very mixed. In Italy and Spain today there are now almost twice as many old people as young people. With so many old and so few young, those countries and many others may be in for hard times during the next few decades. As one population expert in Washington has put it, you can't keep going with the pyramid of civilization standing on its vertex. You can't run a village, much less a country, if most of your people are in nursing homes. Chekhov wrote a short story about a coffin-maker that begins, "The town was small, worse than a village, and in it lived almost none but old people, who died so rarely it was even annoying. And in the hospital and jail there was very little demand for coffins. In short, business was bad."

If we are going to turn our population pyramid upside down in the next decades-and that's what will happen, if it stands at all-then we are looking at a highly unstable situation, socially and politically. "A civilization has the same fragility as a life," said Paul Valery. Challenges to civil values, if they are too great, can lead to civil wars. What happens as the baby boomers go gray all over the world and have to be carried on the backs of their small number of adult children? The lengthening of our life span is the crowning achievement of our species, but the crown is heavy and the head that wears the crown is gray.

Global graying will be one of the great challenges of this century. Demographers will argue about the details for the rest of their lives and ours, just as climate scientists will argue about the details of global warming. But about the very broadest features, there are very few skeptics. We are living longer and staying healthy and vigorous later in life, and every man and woman on the street knows it. You can monitor global graying in your own hair. You can time it by the watch on your own wrist. Barring an apocalypse, the generations of humans alive today can expect to live longer (at least a little longer) than any generation before us.

No matter what else happens with the science of aging, more and more of us will follow it as global graying advances.

Since the problem of mortality will be so much on our minds, whatever our age, we will be watching this science from all sides. We'll argue not only the feasibility of its goals but their desirability.

In France during the summer of 1783, Benjamin Franklin watched the brothers Montgolfier go aloft in a hot-air balloon. "It diminish'd in Apparent Magnitude as it rose," he reported afterward in a letter to the Royal Society, "till it enter'd the Clouds, when it seemed to me scarce bigger than an Orange, and soon after became invisible, the Clouds concealing it." A man in the crowd asked, "What's the use of that?" And Franklin replied, "What is the use of a newborn baby?" He understood that the rise of modern science would mean life itself to us, and although he could not know how far or fast it would travel, he did foresee that the global enterprise would carry us toward ever longer and healthier lives. Later that same year, when the Montgolfiers staged a balloon demonstration before the French court and about 130,000 other onlookers, one Madame d'Houdetot had the same prophetic thought, and found it poignant. Madame d'Houdetot reflected, as she watched the balloon pa.s.sing over Versailles, "Soon they shall discover how to live forever...and we shall be dead."

Now, a generation or two after that New Yorker New Yorker cartoon with the anxious reader of obituaries, we have Web comic strips like XKCD ("A Webcomic of Romance, Sarcasm, Math, and Language"). One strip shows a line of stick figures marching up a hill toward "The Uncomfortable Truths Well." The figures suggest an endless, eternal line of pilgrims bearing questions, which the well answers one by one. And the first question? We know what it is, of course. Quoth the well: "Science may discover immortality, but it won't happen in the next eighty years." cartoon with the anxious reader of obituaries, we have Web comic strips like XKCD ("A Webcomic of Romance, Sarcasm, Math, and Language"). One strip shows a line of stick figures marching up a hill toward "The Uncomfortable Truths Well." The figures suggest an endless, eternal line of pilgrims bearing questions, which the well answers one by one. And the first question? We know what it is, of course. Quoth the well: "Science may discover immortality, but it won't happen in the next eighty years."

Do we want the science to move faster? Do we want a cure for aging? The question of desirability is going to be hard for us. When we examine it closely our thoughts get tangled in it, much as we are entangled with mortality in our bodies. The spiritual and emotional knots are as tight as the biological. We're mortals. We've wrestled with the problem of mortality for thousands of years in the darkest pa.s.sages of Scripture and philosophy. Our poets and artists move us profoundly by struggles without answers. No other scientific program raises so many enormous and imponderable questions, and they are so blithely dismissed by the engineers who would build the dam in the valley of the shadow of death.

We can't know yet if a cure for aging is almost within reach, if it is now low-hanging fruit. But when we turn from feasibility to desirability-when we let ourselves think about science and immortality in the same sentence, and take it seriously, even for a moment-we run into extraordinary turbulence as soon as our thoughts are aloft. Powerful currents run in us, alternating currents of yes and no. We meet internal resistances just as strong as in the body or the cell; and we only half understand them, even though we have been exploring the question "Should we?" for as long as the question "Could we?"

In Paradise Lost Paradise Lost, Milton reminds us that we failed to make ourselves immortal when we reached for the low-hanging apple; in fact, we made things infinitely worse.

Of Man's First Disobedience, and the FruitOf that Forbidden Tree, whose mortal tasteBrought Death into the World, and all our woe...

Milton reinforces the point of the lesson by making Satan fall and suffer at least as horribly as Adam and Eve. He does show some sneaking sympathy for the fallen angel, as Blake observes in a famous line in "The Marriage of Heaven and h.e.l.l"-"NOTE: The reason Milton wrote in fetters when he wrote of Angels & G.o.d, and at liberty when of Devils & h.e.l.l, is because he was a true Poet and of the Devil's party without knowing it." Even so, as Milton announces at the close of his grave and august first verse, the purpose of this epic, the point of "this great Argument," is to "a.s.sert Eternal Providence, and justify the ways of G.o.d to men."

All of Hebrew and Christian Scripture makes this a.s.sertion and insists that the ways of G.o.d are just; to be accepted with or without understanding; to be accepted even in the face of horror. Think of the ghastliest story in the book of Genesis, the testing of Abraham: in Jewish tradition, the episode of the Torah that is recited on the first day of the new year, again and again. Abraham and Sara have a child in their old age, a child so long prayed for and despaired of that when at last he is born they name him Isaac, which means "He laughs." And G.o.d comes to Abraham and commands him to take his son, "your only-one, whom you love, Isaac," up to the mountain and sacrifice him. So early in the morning Abraham saddles his donkey, takes Isaac, splits wood for the sacrifice, and with them goes up to the mountain. They climb the mountain, Isaac carrying the wood and Abraham the torch and the knife.

"Here's the fire and the wood," says Isaac, "but where is the sacrifice?"

And Abraham answers, "G.o.d will provide."

When they come to the place, Abraham builds the pyre, binds Isaac on top of it, and stretches out the knife to slay his son-but G.o.d stops him. "Abraham lifted up his eyes and saw a ram caught in the thicket by its horns. And he offered up the ram in place of his son."

Homer tells the same story of another patriarch, King Agamemnon. When Agamemnon wants to sail for Troy, the wind will not come up to fill the sails of the ships. A priest tells him that it is the will of the G.o.ds that he sacrifice his firstborn daughter, Iphigeneia. So Agamemnon dispatches a messenger to the girl's mother, Clytemnestra, and tells her to send their daughter to him. He says Iphigeneia is to be married to his greatest warrior, Achilles. And the girl comes. In Homer, the king sacrifices his daughter; but in Euripides's play Iphigeneia at Aulis Iphigeneia at Aulis, a G.o.ddess spirits the girl away at the very last moment and subst.i.tutes a deer, which Agamemnon kills instead.

It's curious that this same tortured story should reappear at the core of several religions. In Christian tradition, the hill where Abraham bound Isaac and lifted the knife was Golgotha, also known as Calvary. That is the hill up which G.o.d sent his own son, carrying the wood of the cross on his back, to be sacrificed for the sake of all of humanity, as symbolized by the lamb of G.o.d.

Hindus know the story from the Upanishads. A father, Vajasravasa, pledges to sacrifice all that he has in return for the blessings of heaven. His young son Nachiketas watches as Vajasravasa's cows are led away. "Dear father," the son asks, "to whom wilt thou give me?"

His father is silent.

"Dear father," he asks again, "to whom wilt thou give me?"

Silence.

"Dear father, to whom wilt thou give me?"

"I shall give thee unto Death!"

So the boy descends to the realms of Yama, who is Death. There he learns all the paradoxes of mortality and immortality, in some of the most celebrated poetry of Hindu scripture, which concludes, "When all the ties of the heart are severed here on earth, then the mortal becomes immortal-here ends the teaching."