The Rise and Fall of Alexandria (18 page)

But at this point, just as he was about to make his great discovery, his trail appears to have gone cold. None of Aristarchus’s other work survives, and his brilliant idea might have remained unknown in the modern world were it not for a small aside in a book by another great mathematician: Archimedes.

In his book
The Sand Reckoner,
Archimedes set out to demonstrate methods for dealing mathematically with extremely large numbers, such as the number of grains of sand which would fill the universe (hence the title of his book). Of course to arrive at the largest number possible, he had to find a description of the largest theoretical universe known in which to place his grains, and for that he turned to Aristarchus. Having explained to his patron, King Gelon, that most astronomers believed the earth to be the center of the universe, around which everything else rotated, he added almost as an aside:

 
Here then was Aristarchus’s great thought, preserved only as a reference in another book. Archimedes for his part did not even believe it to be true, only being interested in the sheer scale of the model he proposed.

The response to Aristarchus’s hypothesis of a heliocentric solar system was perhaps to be predicted and may in itself help to explain why so few of his own works survive. Contemporaries were horror-struck by the new role this Alexandrian astronomer gave to the earth and, by implication, to the people on it. How dare he take away their special position at the very heart of creation? One of them, by the name of Cleanthes, wrote a treatise entitled simply
Against Aristarchus.
This has since been lost, so we don’t know on what grounds he attacked Aristarchus, but Plutarch would later comment that Cleanthes

 
We don’t know if Aristarchus was ever indicted, or whether a trial ensued; it would perhaps seem unlikely in the liberal atmosphere of Alexandria, though we should not forget Socrates’ fate and the threats laid upon both Plato and Aristotle. But at the very least this bold new theory provoked a reassertion of the official orthodoxy from several scholars, including Dercyllides, who argued somewhat pompously the need to assert that the Platonic model of a fixed earth with its “Hearth of the house of the gods” countered by moving planets and the rest of the heavens was correct. He claimed that it was essential to reject those who brought to rest the things that move and set in motion the things that by their nature and position are unmoved, insisting that such a supposition was contrary to the theories of mathematicians.

In the end these reactionary responses held sway. Aristarchus had no significant followers in his own generation or the following ones, and his only known disciple was a Chaldean named Seleucus who lived by the Tigris River and adopted Aristarchus’s teachings around 150 BC. Why this rejection of Aristarchus should happen is one of the greatest riddles of the ancient world. Aristarchus’s heliocentric universe seems so clearly true to us, who have the benefit of modern science and space travel to help our imaginations, that it’s hard to envisage what it must have been like to be committed to an earth-centered view of the cosmos. Yet that was the view that prevailed for thousands of years throughout antiquity, and which would continue as the only acceptable model of the solar system until the sixteenth century AD.

But there are two other profound reasons why Aristarchus’s beautifully mathematical, mechanical universe was too far ahead of its time to be acceptable, even to the scholars at the museum in Alexandria. First, we need to return to the age-old dichotomy between faith and reason, or religion and rationality. Even the great Plato had comparatively recently insisted that while our fallen, corrupted world may be analyzable using rationality, the really pure, uncontaminated cosmic bodies were to be found in the skies, or rather the heavens. Here were the seats of pure spirituality, divine beings if you like. To reduce these heavenly spheres to mere lumps of rock shunting around an infinitely huge void was tantamount to heresy: hence Cleanthes’ determination to indict Aristarchus for
impiety
—godlessness—not bad science.

But at an even more profound level, great minds like Archimedes balked at the idea of a sun-centered universe because it took the spotlight off us humans. An earth-centered universe is also an ego-centered universe. Why should the gods create the universe at all if not to give us humans somewhere to play, and to puzzle about? Plato had already decreed that humans were at the very zenith of creation, and that we had already gone through five phases of evolution, the last, most elevated phase being that of the philosopher—the lover of wisdom. Aristarchus’s universe was a vast and lonely place, where the earth was relegated to the role of just another planet circling around a fixed sun, shrouded in a vault of impossibly distant stars. No god marked out this earth as special—it had become just another wanderer. To demote the earth to this was to deny that the universe was built
by
the gods,
for
us. That was like denying both our descent and our ascent. Most preferred a more comfortable, human-centered universe, and this conception would survive right down to Darwin, when he scandalized Victorian society with his notion that people might be descended not from God but from mere apes.

So the cometlike genius of Aristarchus flared across the Alexandrian skies, then vanished. But not forever. In AD 1543 Copernicus published his revolutionary heliocentric model of the universe just before his death, which possibly occurred only hours after he received the first printed copy of the book. It has even been argued that Copernicus may have died of fear—fear of the wrath of the Catholic Church at a man of the cloth daring to suggest that the earth goes around the sun and not vice versa. Certainly we know that he sat upon his manuscript for decades, steadfastly refusing to publish it.

More recent research reveals, however, that his anxieties may have been driven by guilt as much as by fear. For in the original handwritten manuscript there were several references to Archimedes’
The Sand Reckoner,
which of course contained his summary of Aristarchus’s book on the heliocentric universe. These references have, however, been systematically removed from the printed version of the text, and no mention is made either of Archimedes’ book or of Aristarchus. And still today nearly all of us credit Copernicus with the “discovery” of the true nature of our planet’s motion around the sun. It’s particularly ironic that Aristarchus is sometimes referred to as the “Greek Copernicus” when in fact it is Copernicus who should be referred to as the “Polish Aristarchus.”

Aristarchus’s books, including his work on the sun-centered universe, were of course lodged in the great library in Alexandria, which is very probably where Archimedes read them (he was about twenty-five years younger than Aristarchus). While Aristarchus’s great ideas never caught on in his lifetime, his work was known and read, proving that from just a small observatory on the grounds of a temple, Alexandria was already turning the universe—and the world with it—on its head. The gods had begun to release their grip, leaving humans to stagger into the daylight and begin to explore their world.

CHAPTER EIGHT

William Shakespeare,
Antony and Cleopatra

 
 
W
hile Aristarchus put the earth and heavens in motion, it would fall to another Alexandrian to attempt the seemingly impossible and actually measure them. In the process he would transform disciplines as diverse as mathematics, astronomy, and geography forever. Aristarchus had told the Alexandrians we lived on a planet ceaselessly circling our sun, but it would be Eratosthenes who would describe the nature of the craft on which he traveled.

Eratosthenes, son of Aglaus, was born around 275 BC in the city-state of Cyrene (now Shahat) in present-day Libya. It was a city firmly bound into the Alexandrian world, having been conquered by Ptolemy I, but one with a reputation for freethinking, encouraged by the liberal constitution that the first Greek pharaoh had granted it. Even in Eratosthenes’ youth the city already had many famous institutions, including a medical school, and many famous sons, among them the philologist Lysanias and the great Callimachus himself, both of whom personally tutored the young man. Some years before it had also nurtured one of the more individual thinkers of the day, Aristippus, a companion of Socrates, and his grandson (also called Aristippus), who had founded his own Cyrenaic school of philosophy. Here it was taught that only the present moment exists and that immediate pleasure is the only purpose of any action.

It was to Athens, however, that Eratosthenes was soon drawn, to the places where Plato and Aristotle had taught, and here he came under the influence of the Skeptics. At the Academy the young Cyrenian met the greatest philosopher of his day and the institution’s
scholarch
(or director). Arcesilaus was a man famed for his wide circle of friends and correspondents across the Mediterranean; his quick wit; his broad interests; his love of wine (one source reports he died during a drinking bout when seventy-five years old); and, according to some sources, his harsh teaching methods. As a Skeptic, Arcesilaus taught his pupils to argue both sides of a question, to see a problem from other angles, and then to remain “skeptical,” that is, to withhold judgment. In arguing against the Stoics, some of whom Eratosthenes also counted among his friends and tutors, the Skeptics proposed that one cannot rely entirely upon one’s senses and that the Stoical view that truth came from clear perception followed by certainty was wrong. It was a philosophy that would have a profound impact on Eratosthenes, not merely in his philosophical musings but in the actual practical business of his life.

Clearly during his time in Athens the members of the Academy had already noted something special in Eratosthenes, and he had soon joined the international network of thinkers, which led him inexorably toward the Ptolemaic court, Alexandria, and the great library. His Athenian master had after all been a pupil of Aristotle’s friend and successor, Theophrastus, and the Alexandrian project must already have been well known to him. He was also becoming known to the Ptolemies. For all the peace and glamour of Ptolemy III’s court, one problem did play on the pharaoh’s mind: Who would tutor his son? For every Ptolemy this was a matter of vital importance, as over the preceding three generations they had each, in turn, benefited from the most privileged education available. Ptolemy I had learned from Aristotle, his son had been taught by Strato of Lampsacus, and his son by Apollonius of Rhodes, author of
Jason and the Argonauts.
When news reached Alexandria of this bright new star at the Academy, Ptolemy III knew he had found his man, and the invitation was duly issued.

At the moment Eratosthenes stepped ashore in the Great Harbor of Alexandria, one of the brightest periods in the city’s history began. Yet with a certain irony, even as he climbed the marble steps to the palace to meet his new charge, he was approaching the little boy who, years later, would begin to bring the whole Ptolemaic edifice tumbling down.

For now, however, this was the greatest opportunity of the young philosopher’s life. He was under the protection and patronage of one of the wealthiest and most liberal rulers of his day, and before him lay the full resources of the museum and library, where he could explore the entirety of the knowledge of the world. And that is exactly what Eratosthenes wanted to do—he wanted to know everything.

Court life must have been tiresome for the young tutor as he struggled to instruct the self-indulgent young Ptolemy IV, who, unlike his forefathers, seems to have taken little interest in learning any of the skills that had created his dynasty. But there was a greater reward for a patient tutor close at hand. It was not long after arriving in Alexandria that Eratosthenes became not only a member of the museum, but the librarian of the great library, following the death (or possibly the retirement) of Apollonius of Rhodes.

Now began an explosion of work in a huge range of fields. The scholars in the pharaoh’s pay were not, like modern academics, required to become specialists in one subject. There were certainly some, the physicians and mathematicians among them, who were highly focused on a single area, but the work of a philosopher in Alexandria was generally considered to include the exploration of all fields of knowledge and thought. The boundaries of art and science had not yet been fenced off, and a great mind could wander freely. Men such as Eratosthenes might write about mathematics and poetry, astronomy and literary criticism, comedy and geography. And that is exactly what he did.

The curse of Alexandria is also Eratosthenes’ curse, and today almost none of his original works survive, but their impact was such that we still have glimpses, caught in references and quotes in later works. We know that at this time he produced twelve books entitled
On Ancient Comedy,
dealing with the history, language, and authorship of Greek comic plays. He also compiled a star catalog of 675 stars and books on the constellations and the mythology surrounding them. Having compiled a list of Olympic victors, he went on to write his
Chronology,
the first scientific attempt to fix the major dates of political and literary history from the siege of Troy, through the Dorian migration and the first Olympiad, up to his own time. And to ensure that no future scholar had such trouble calculating the dates for ancient events, he drew up a sophisticated calendar, complete with leap years, a system Julius Caesar would later “borrow” and claim as his own—the Julian calendar.