Roman rule engendered among those it oppressed a growing scorn for material wealth, a heightened regard for ethical values, and a willingness to imagine that their earthly sufferings were but a preparation for a better life to come. The conflict between this essentially spiritual, otherworldly outlook and the stolid practicality of Rome crystallized in the interrogation that Pontius Pilate, a prefect known for his ruthlessness and legal acumen, conducted of the obscure Jewish prophet Jesus of Nazareth.
The world knows the story. Pilate asked Jesus, “Are you the king of the Jews?”
“My kingdom is not of this world,” Jesus replied.
“Are you a king, then?”
“You say I am a king,” Jesus replied. “To this end was I born, and for this cause I came into the world, that I should bear witness to the truth. Everyone that is of the truth hears my voice.”
“What is truth?” asked Pilate.9
Jesus said nothing, and was led off to execution, and his few followers dropped from sight. Yet within two centuries his eloquent silence had swallowed up the words of the law, and Christianity had become the state religion of Rome.
Science, however, fared no better in Christian than in pagan Rome. Christianity, in its emphasis upon asceticism, spirituality, and contemplation of the afterlife, was inherently uninterested in the study of material things. What difference did it make whether the world was round or flat, if the world was corrupt and doomed? As Saint Ambrose put it in the fourth century, “To discuss the nature and position of the earth does not help us in our hope of the life to come.” Wrote Tertullian the Christian convert, “For us, curiosity is no longer necessary.”
To the Christians, the fall of Rome illustrated the futility of putting one’s trust in the here and now. “Time was when the world held us fast to it by its delight,” declaimed Pope Gregory the Great, seated on a marble chair amid the flickering candles of the chapel of the Catacomb of St. Domitilla in Rome at the close of the sixth century (by which time the city had been sacked five times). “Now ’tis full of such monstrous blows for us, that of itself it sends us home to God at last. The fall of the show points out to us that it was but a passing show,” he said, advising the somber celebrants to “let your heart’s affections wing their way to eternity, that so despising the attainments of this earth’s high places, you may come unto the goal of glory which ye shall hold by faith through Jesus Christ, our Lord.”10
Christian zealots are alleged to have burned the pagan books in the library of Alexandria, and Muslims to have burned the Christian books, but the historical record of this great crime is subject to dispute on both counts; in any event, the books went up in smoke. The old institutions of learning and philosophy, most of them already in decline, collapsed under the rising winds of change. Plato’s Academy was closed by Justinian in A.D. 529; the Sarapeum of Alexandria, a center of learning, was razed to the ground by Christian activists in A.D. 391; and in 415 the geometer Hypatia, daughter of the last known associate of the museum of Alexandria, was murdered by a Christian mob. (“They stripped her stark naked,” an eyewitness reported. “They raze[d] the skin and ren[t] the flesh of her body with sharp shell, until the breath departed out of her body; they quartered] her body; they [brought] her quarters unto a place called Cinaron and burn[ed] them to ashes.”11)
Scholars fled from Alexandria and Rome and headed for Byzantium—followed closely by the Roman emperor himself, after whom the city was renamed Constantinople—and the pursuit of science devolved to the province of Islam. Encouraged by the Koran to practice taffakur, the study of nature, and taskheer, the mastery of nature through technology, Islamic scholars studied and elaborated upon classics of Greek science and philosophy forgotten in the West. Evidence of their astronomical research is written in the names of stars—names like Aldebaran, from Al Dabaran, “the follower;” Rigel, from Rijl Jauzah al Yusra, “the left leg of the Jauzah;” and Deneb, from Al Dhanab al Dajajah, “the hen’s tail.”
But the Arabs were enchanted by Ptolemy, and envisioned no grander cosmos. Aristarchus’ treatise on astronomical distances was translated in the early tenth century by a Syrian-Greek scholar named Questa ibn Luqa, and an Arabic secret society known as the Brethren of Purity published an Aristarchian table of wildly inaccurate but robustly expansive planetary distances, but otherwise little attention was paid to the concept of a vast universe. The generally accepted authority on the scale of what we today call the solar system was al-Farghani, a ninth-century astronomer who, by assuming that the Ptolemaic epicycles fit as tightly as ball bearings between the planetary spheres—“there is no void between the heavens,” he asserted—estimated that Saturn, the outermost known planet, was eighty million miles away.12 Its true distance is more than ten times that.
The Islamic devotees of Ptolemy, however, inadvertently undermined the very cosmology they cherished, by transmuting Ptolemaic abstractions into real, concrete celestial spheres and epicycles. So complex and unnatural a system, palatable if regarded as purely symbolic, became hard to swallow when represented as a genuine mechanism that was actually out there moving the planets around. The thirteenth-century monarch King Alfonso (“the Learned”) of Castile is said to have remarked, upon being briefed on the Ptolemaic model, that if this was really how God had built the universe, he might have given Him some better advice.
But that was many long, dark centuries later. The last classical scholar in the West was Ancius Boethius, who enjoyed power and prestige in the court of the Gothic emperor Theodoric at Ravenna until he backed the losing side in a power struggle and was jailed. In prison he wrote The Consolation of Philosophy, a portrait of the life of the mind illuminated by the fading rays of a setting sun. There, Boethius contrasts the constancy of the stars with the unpredictability of human fortune:
Creator of the starry heavens,
Lord on thy everlasting throne,
Thy power turns the moving sky
And makes the stars obey fixed laws
…………….
All things thou holdest in strict bounds,—
To human acts alone denied
Thy fit control as Lord of all.
Why else does slippery Fortune change
So much, and punishment more fit
For crime oppress the innocent?13
In words the Greek Stoics would have appreciated, the muse of philosophy upbraids Boethius for his self-pity. “You are wrong if you think Fortune has changed towards you,” she tells him. “Change is her normal behavior, her true nature. In the very act of changing she has preserved her own particular kind of constancy towards you.”14
In Boethius, the universe of Ptolemy is reduced to a symbol of resignation to the vicissitudes of fate:
Consider how thin such fame is and how unimportant. It is well known, and you have seen it demonstrated by astronomers, that beside the extent of the heavens, the circumference of the earth has the size of a point; that is to say, compared with the magnitude of the celestial sphere, it may be thought of as having no extent at all. The surface of the world, then, is small enough, and of it, as you have learnt from the geographer Ptolemy, approximately one quarter is inhabited by living beings known to us. If from this quarter you subtract in your mind all that is covered by sea and marshes and the vast area of desert by lack of moisture, then scarcely the smallest of regions is left for men to live in. This is the tiny point within a point, shut in and hedged about, in which you think of spreading your fame and extending your renown.15
Boethius was executed in 524, and with the extinguishing of that last guttering lamp the darkness closed in. The climate during the Dark Ages grew literally colder, as if the sun itself had lost interest in the mundane. The few Western scholars who retained any interest in mathematics wrote haltingly to one another, trying to recall such elementary facts of geometry as the definition of an interior angle of a triangle. The stars came down: Conservative churchmen modeled the universe after the tabernacle of Moses; as the tabernacle wa
s a tent, the sky was demoted from a glorious sphere to its prior status as a low tent roof. The planets, they said, were pushed around by angels; this obviated any need to predict celestial motions by means of geometrical or mechanical models. The proud round earth was hammered flat; likewise the shimmering sun. Behind the sky reposed eternal Heaven, accessible only through death.
*Archimedes concluded that it would take 1063 grains of sand to fill the Aristarchian universe. The American cosmologist Edward Harrison points out that 1063 grains of sand equals 1080 atomic nuclei, which is “Eddington’s number”—the mass of the universe as calculated in the 1930s by the English astrophysicist Arthur Stanley Eddington. So Archimedes, in underestimating the size of the universe but imagining it to have a matter density much higher than it does, arrived at a total amount of cosmic matter that wasn’t far from Eddington’s twentieth-century estimate.
3
THE DISCOVERY OF THE EARTH
There will come a time in the later years when Ocean shall loosen the bonds by which we have been confined, when an immense land shall be revealed … and Thule will no longer be the most remote of countries.
—Seneca
The sea was like a river.
—Christopher Columbus
The reawakening of informed inquiry into the nature of cosmological space that we associate with the Renaissance had its roots in an age of terrestrial exploration that began at about the time of Marco Polo’s adventures in China in the thirteenth century and culminated two hundred years later with Columbus’s discovery of America. Astronomy and the exploration of the earth had of course long been related. Navigators had been steering by the stars for millennia, as evidenced by the Chinese practice of calling their blue-water junks “starry rafts” and by the legend that Jason the Argonaut was the first man to employ constellations as an aid to memorizing the night sky. When Magellan crossed the Pacific, his fleet following an artificial star formed by a blazing torch set on the stern of his ship, he was navigating waters that had been traversed thousands of years earlier by the colonizers of Micronesia, Australia, and New Guinea—adventurers in dugout canoes who, like Jason, carried their star maps in their heads. Virgil emphasized the importance of sighting the stars in his account of Aeneas’ founding of Rome:
Not yet had night,
Whirled onward by the hours,
Reached her mid course, when from his couch
The ever watchful Palinurus arose.
He examined every wind, listening
To the breeze, and marked all the stars
That swim across the silent heavens:
Arcturus, and the rainy Hyades;
The twin bears, and Orion armed in gold.
When he was satisfied that all
Was calm in the cloudless sky,
From off the stern he sounded the signal call.
We struck the camp, essayed our course anew,
And spread our sail wings.
When dawn was reddening,
And the stars were being put to flight,
Far off we beheld the shadowy hills,
Of Italy, low lying. “Italy!”
Explorers of dry land found the stars useful, too; American Indians lost in the woods took comfort in the presence of Father Sky, his hands the great rift that divides the Cygnus-Sagittarius zone of the Milky Way, and escaped slaves making their way north through the scrub pines of Georgia and Mississippi were admonished to “follow the drinking gourd,” meaning the Big Dipper. Ptolemy employed his considerable knowledge of geography to aid his studies of astronomy; his assertion that the earth is but a point compared to the celestial sphere was based in part upon the testimony of travelers who ventured south into central Africa or north toward Thule and reported seeing no evidence that their wanderings had brought them any closer to the stars in those quarters of the sky.1
Thus, though the principal motive for the new wave of European exploration was economic—European adventurers stood to make a fortune if they could “orient” themselves, by navigating an ocean route to the East—it is not surprising to learn that one of its instigators was an astronomer. He was a Florentine named Paolo dal Pozzo Toscanelli, and he emphasized that knowledge as well as wealth was to be found in the East. Asia, Toscanelli wrote enticingly to Christopher Columbus,
is worthy to be sought by the Latins not only because immense wealth can be had in the form of gold, silver, gems of every kind, and spices which are never brought to us; but also because of the learned men, wise philosophers and astrologers by whose genius and arts those mighty and magnificent provinces are governed.2
Much of the romance that colored the Western image of the East had come from Marco Polo’s extraordinary book recounting his equally extraordinary travels in China. Marco came from Venice, itself no backwater, but nothing had prepared him for the likes of Hangchow, which he visited in 1276 and from which he never quite recovered. “The greatest city in the world,” he called it, “where so many pleasures may be found that one fancies himself to be in Paradise.” Hangchow stood on a lake amid jumbled, misty mountains, the literal depiction of which by Sung landscape painters still strikes Western eyes as almost too good to be true. “In the middle of the lake,” Marco reported,
there are two islands, on each of which stands a palatial edifice with an incredibly large number of rooms and separate pavilions. And when anyone desired to hold a marriage feast, or to give a big banquet, it used to be done at one of these palaces. And everything would be found there ready to order, such as dishes, napkins and tablecloths and whatever else was needed. These furnishings were acquired and maintained at common expense by the citizens in these palaces constructed by them for this purpose.3
Ornately carved wooden boats were available for hire, the largest of them capable of serving multiple-course banquets to scores of diners at a sitting. Skiffs maneuvered alongside the larger boats, carrying little orchestras and “sing-song girls” in bright silk dresses and boatmen selling chestnuts, melon seeds, lotus roots, sweetmeats, roast chicken, and fresh seafood. Other boats carried live shellfish and turtles, which in accordance with Buddhist custom one purchased and then threw back into the water alive. The lake was clear, thanks to strict antipollution ordinances, and its banks were given over to public parks—this a legacy of Hangchow’s revered prefect Su Tung-p’o, a gifted poet who was often in trouble with the authorities. Wrote Su:
Drunk, I race up Yellow Grass Hill,
Slope strewn with boulders like flocks of sheep.
At the top collapse on a bed of stone,
Staring at white clouds in a bottomless sky.
My song wings to the valley on long autumn winds.
Passers-by look up, gaze southeast,
Clap their hands and laugh: “The governor’s gone mad!”4
All of which was a long way from the cold stone walls and plainsongs of northern Europe, and even from the commercial bustle and guile of Venice.
Bolstering the travelers’ tales was tangible evidence of Asian glory, in the form of silks and lacquer boxes and spices and drugs that had reached Europe overland. The Silk Road by which these treasures arrived, however, had long been a costly bucket-brigade of middlemen and brigands, and was now being constricted by the Black Death and the retreat of the Mongol khanates before an expanding Islamic empire. By the fifteenth century the European powers were ready to try reaching the East on their own, by sea.
The epicenter of this venturesome new spirit was Sagres, a spit of land at the southwesternmost tip of Europe that juts out into the ocean like a Renaissance Cape Canaveral. There, in 1419, a spaceport of sorts was established by Prince Henry the Navigator. A devout, monomaniacal Christian in a hair shirt, his eyes baggy with the fatigue of overwork and the vexation of debt, Henry was the first to explore the coast of Africa and to exploit its riches in gold, sugar, and slaves, and the first to navigate a seaway around Africa to Asia.
His library at Sagres contained an edition of Marco Polo (translated by
his wandering brother Pedro) and a number of other books that encouraged Henry’s belief that Africa could be circumnavigated, opening up a seaway to the East. The evidence, though fragmentary, was tantalizing. Herodotus in the fifth century B.C. recounted (though he did not believe it) a story that Phoenician expeditionaries had rounded Africa from the east, eventually finding that while sailing west they had the sun on their right—which Henry understood, as Herodotus did not, to mean that they were south of the equator. Two centuries later, Eudoxus of Cyzicus (no relation to the astronomer) was reported in a book by Strabo the geographer to have found, in Ethiopia, the sculptured prow of a wrecked ship that the natives said had come from the west; Eudoxus took the prow home with him to Egypt and was told by the local sailors and traders that it belonged to a vessel that had sailed out through the Columns of Hercules, never to be seen again. In the Periplus of the Erythraean Sea, an anonymous geography dating from the first century A.D., Henry could read that “beyond the town of Rhapta”—i.e., opposite Zanzibar—“the unexplored coast curves away to the west and mingles with the Western Ocean.”5
Coming of Age in the Milky Way Page 4