The Cave and the Light

by Arthur Herman

  As a member and then director of the Lyceum, Strato made two crucial decisions for the future of Western thought. The first was to insist that scientific research had to be free from any restraints by theology (he himself seems to have been a materialist and atheist) or philosophy, including ethics. Instead, according to a knowledgeable ancient authority, “[Strato] devoted himself entirely to the investigation of nature.”18 It is under Strato that the heirs of Aristotle took the first tentative steps toward the idea of pure science, that an investigator must be free to pursue his work regardless of where it leads or what inconvenient truths it discovers—or even what comfortable worldviews it upsets, including Aristotle’s own.

  It is hard to believe this is what Aristotle intended.19 He had seen his natural philosophy, including his physics and astronomy, as a complete and unshakably true picture of reality. But by stressing the power of observation as the main source of knowledge, he had let the genie run free. His students, even the loyal Theophrastus, felt compelled to question his theories based on new data or new observations. Strato contrived physical tests to bring Aristotle’s fondest assumptions under scrutiny. His work on creating an artificial vacuum, which Aristotle had said was impossible, may be the first true scientific experiment.20

  In this way and almost in spite of himself, from the moment he first picked up a lungfish on the beach and wondered what was inside, Aristotle had created a Western scientific method that was destined to be permanently open-ended. It would be based on observation, analysis, and making fine distinctions (diairein) or divisions, instead of worrying about the Big Picture. It became the vehicle for research into every aspect of nature. It would lead in directions Aristotle himself never imagined, and not just in Athens.

  Becoming an advocate of pure scientific research was Strato’s first momentous decision. We don’t know exactly when he came to his second, which was to leave Athens for Alexandria in Egypt. We do know it was before 287 BCE and came at the invitation of Egypt’s ruler, Ptolemy I, who wanted a tutor for his son and heir, Ptolemy Philadelphus. In any case, Strato’s arrival in that thriving port city was a landmark event in the history of Greek science. At one stroke Strato was leaving Athens, the ancient city of philosophers, intellectuals, and cosmopolitan aristocrats, for Alexandria, a new city of international businessmen, mathematicians, and engineers.

  Before Alexander founded the city at the mouth of Nile thirty or so years earlier in 332, there had been nothing but sand dunes and swamps and scattered fishing villages. But the area formed a natural harbor, and in a couple of decades Alexandria became one of the richest urban centers on the Mediterranean.

  In a sense, it was the first modern city. It stood at the confluence of three ancient cultures: Greece, Egypt, and the Middle East, including Babylon. People of every color and religion from Syria, Asia Minor, Iberia, Phoenicia, Nubia, the Arabian peninsula, Persia, and India swarmed its streets, did business in its shops, and unloaded their goods in its warehouses. Its Jewish quarter (according to the historian Josephus, Jews started arriving shortly after Alexander’s death) covered two of the city’s five principal districts. Jewish Alexandria became the home of shopkeepers, craftsmen, and artisans and a dozen synagogues.21 Jewish relations with Greeks and Egyptians alike were respectful and amiable. People were too busy making money to fight over religious or ethnic differences.

  No other ancient city demonstrated so powerfully Aristotle’s assertion that “a difference of capacities among its members enables them to attain a higher and better life by the mutual exchange of their different services.” From that point of view alone, Alexandria was already Aristotle’s city.

  Its ruler was the Macedonian king of Egypt Ptolemy I, one of Alexander’s former generals, a tough, vigorous man who continued to command armies in the field until he was in his eighties. Ptolemy had always wanted his capital city to have a strong connection with Aristotle and the Lyceum. Perhaps he had learned on his campaigns with Alexander the value of Aristotle’s kind of precise scientific research—and the value to a ruler of this kind of intellectual patronage.22 Ptolemy had asked Aristotle himself to set up a library in Alexandria. Later, he invited Theophrastus to do the same.

  In the end, he had to be satisfied with Strato of Lampsacus as his son’s tutor. However, that was enough. Strato saw the situation clearly as soon as he got off the boat. Here was a rich, thriving city, a metropolis (as the Hellenistic Greeks termed it) teeming with alert, intelligent people from every part of Europe, Africa, and Asia. And here was a rich, powerful patron, Ptolemy I, determined to make Alexandria the most glorious city in the world and to bring his own reputation out from under the shadow of its illustrious founder.

  Strato must have smiled at his good fortune. The Ptolemies father and son were the perfect foils for his plan to give the Lyceum a new importance and freedom. Alexandria was also the perfect place to give Aristotle a new boost as the godfather of Western science.

  * * *

  * This was Cleitomachus, who took over the Academy in 127–26 BCE.

  † The best-known example is probably Gaius Cassius Longinus, Brutus’s friend and fellow plotter against Julius Caesar, who is immortalized in Shakespeare’s Julius Caesar with the line “The fault, dear Brutus, is not in the stars, but in our selves …” Good Epicurean advice, although Brutus himself, despite his obvious Stoic leanings, was an alumnus of the Academy.

  ‡ The story is that Epictetus had once had a sadistic owner who left him permanently lame. When his master was twisting his leg, Epictetus only smiled and said, “You will break it.” And when it broke, “I told you so.” This indifference to physical pain would be a hallmark of Stoicism, particularly the Roman kind. It persists in the most familiar Stoic character from television, the pointy-eared Vulcan hero Mr. Spock of Star Trek.

  § This quotation is often credited to the Roman Stoic Seneca (see chapter 9). Epictetus, however, gave it its original Greek formulation, quoting Zeno’s successor Cleanthes (c. 330–231 BCE).

  ‖ Heraclides never lost sight of Platonic astronomy’s ultimate goal and liked to quote Pythagoras: “Beatitude is the knowledge of the perfection of the numbers of the soul.”

  Seven

  KNOWLEDGE IS POWER

  Give me a lever and a place to stand, and I shall move the earth.

  —Archimedes (287–12 BCE)

  It was shortly after arriving in Alexandria that Strato of Lampsacus became King Ptolemy’s principal adviser on all matters intellectual and scientific. Over the next several years, he would use that position to create the ancient world’s most important research center, Alexandria’s Mouseion, or Museum. Just as Alexandria was Aristotle’s city, so its Museum would be the centrifuge for spreading Aristotle’s methods and ideas across the ancient world.

  We have no record of when or how Strato suggested creating the Museum and no idea when Ptolemy, the wily old general, gave his approval. Still, Strato clearly meant it to be a kind of branch campus of the Lyceum. Alumni of the Lyceum in Athens, the so-called Peripatetics, flocked to Alexandria to pursue their scientific research. Since, as its name implied, the Museum was dedicated not just to science but to all the Muses, its Peripatetic staff also launched the first systematic study of Greek literature and language (following in the footsteps of Aristotle’s own work in his Rhetoric and Poetics).* Under Strato’s former pupil Ptolemy II Philadelphus, the Museum grew still larger and more prestigious. It was the Hellenistic world’s equivalent of Harvard, Oxford and Cambridge, and MIT all rolled into one.

  The rules of the Museum itself seem to have been based on the Lyceum, with students and scholars taking meals together and living under the same roof. The salaries of its teachers and officials were even tax-exempt.1 And Strato and his staff not only had all of Greek learning at their fingertips, they could also draw on Egypt’s two-millennia-old tradition of study of mathematics and geometry, as well as astronomy and medicine.

  Soon Alexandria’s Museum was a busy hive of intellec
tual labor, even as Strato and his Peripatetic colleagues provided the impetus for another act of Ptolemaic patronage, the Great Library. It was probably inspired by Aristotle’s library at the Lyceum and embodied a key Aristotelian principle: that the starting point of all true knowledge is not (contrary to Plato) abstract reasoning, but the collection and comparison of individual specimens, whether they be plants and shellfish or books and manuscripts.2

  Like that of the Museum, the Great Library’s history is shrouded in conflicting accounts and legend. We can be reasonably sure its first director was Demetrius of Phalerum, a shrewd and strong-willed figure with deep connections to the Lyceum in Athens. Demetrius seems to have brought a heavy influx of Peripatetic influence into the choosing of the library’s collections and in the selection of its staff. In the end, Demetrius assembled no fewer than 120,000 separate titles, arranged in room after room of neatly rolled papyrus scrolls, including thousands of precious Egyptian and Babylonian texts. The Great Library was a treasure trove for research not only for science but for history, literature, philosophy, and theology. At some point (according to the ancient scholar Athenaeus), a former student of Theophrastus’s sold Ptolemy II his teacher’s complete library, including many works Aristotle himself had collected. In this way, the Great Library of Alexandria became Aristotle’s physical as well as intellectual legacy to the ancient world.3 Tapping into these unmatched resources, including forty separate rolls of Aristotle’s Analytics,4 scholars in Alexandria could now conduct research on a scale never imagined by Aristotle or his heirs in Athens, or indeed anyone else.5 It triggered a transformation of Greek science, beginning with medicine.

  Library of Alexandria

  The heroic figure in ancient medical research between Hippocrates and the great Galen is Herophilus of Chalcedon. Galen’s own work would be unimaginable without him. Born around 335 BCE, Herophilus’s first teacher came from Cos, the home island of Hippocrates and long a center of medical studies. However, Herophilus’s most important work was all done in Alexandria, probably in connection with the Museum. Certainly his students taught medicine there.

  Herophilus pioneered the study of the neurovascular system. He proved, for example, that the nervous system’s center was (contrary to Aristotle’s own teaching) the brain. He explored the prognostic possibilities of taking a patient’s pulse, and he helped to create a standard medical vocabulary based on Greek words like haima for blood, as in hematoma (toma from the Greek tumma, or oma), and gaster for stomach, as in gastritis that is still used today.6

  His biggest contribution, however, was in the study of anatomy. Following Aristotle’s example with animals, he turned to dissection to discover what was going on inside the human frame. His curiosity was insatiable. Some ancient sources claim he turned to human vivisection in his work, including experiments on criminals handed over to him by the Ptolemaic government.7

  Are the stories true? Given the fact that a couple of centuries later Galen mentions testing new poisons on condemned criminals, and the fact that slaves were routinely tortured to extract information in legal cases, there is no reason to doubt them. Centuries later, the Christian critic Origen blamed Herophilus for carrying free scientific inquiry too far and called him “that butcher who cut up innumerable human beings so that he could study nature.” It was a first hint of the battles to come between religion and science over what we call medical ethics.8

  It may be unfair to Herophilus to have Jack Kevorkian or Josef Mengele hovering over his reputation. Certainly the corpus of his anatomical writings might have been scientific Alexandria’s greatest gift to posterity, if it had not perished in the great fire that devastated large portions of the Great Library in 48 BCE.†9

  Meanwhile, one of Strato’s pupils, Aristarchus of Samos, was busy transforming astronomy. He set out to study the summer solstice, that day in the calendar when daylight hours are longest. Aristarchus’s observations led him to propose a completely new model of the universe and solar system, based on the hypothesis that the planets revolved around the sun and that the earth itself revolved every twenty-four hours around its axis. Aristarchus was also a formidable mathematician, who made calculations of the distance from the earth to the sun and the diameter of the sun based on solar eclipses.

  Aristarchus’s heliocentric theory was an astonishing leap into the future. However, it found no buyers among other Hellenistic astronomers. They took a straightforward geometric, rather than dynamic, view of motion. As orthodox Aristotelians, they couldn’t understand the idea of force or acceleration except in terms of something pushing something else (it will take Galileo and Newton to set that issue straight). Nor could they understand why, if the earth really did rotate, everything not tied down or rooted in the ground did not eventually fly off in the opposite direction.10

  It’s not known how Aristarchus answered what, given the assumptions of the time, were reasonable objections backed by the authority of Aristotle himself, or even if he did. In the end, Greek astronomers preferred to stick to Aristotle’s “celestial spheres” to explain the movement of the planets and the stars.‡ The earth remained the center of the universe for another two thousand years. Even so, the mathematical computations of Alexandrian astronomy remained at a very high level. The philosopher of mathematics Bertrand Russell has called them “works of astonishing genius.”11

  This amazing—if ultimately misleading—work culminated in the treatises of the great Ptolemy (no relation to the ruling dynasty) in the first century CE. Ptolemaic astronomy was Alexandria’s last word on the geocentric view of the cosmos. It would remain Europe’s principal guide to astronomy until the Renaissance. Ptolemy’s greatest claim to authority, his firm reliance on Aristotle, was also his greatest limitation and foreshadowed a pattern that would become all too familiar later on.

  Ptolemy and other Aristotle disciples would find themselves having to “save the appearances,” as the commentator Simplicius called it a couple of centuries later: in other words, reinterpreting any new empirical evidence so that it shored up, and never contradicted, Aristotle’s own assumptions about the universe and nature.12 The Aristotelian schoolmen of medieval Paris would do the same thing. Still later, the poet John Milton would mock them all in Paradise Lost:

  Hereafter, when they come to model Heav’n,

  And calculate the stars, how they will wield

  The mighty frame: how build, unbuild, contrive

  To save appearances; how gird the sphere

  With centric and eccentric scribbl’d o’er,

  Cycle and epicycle, orb in orb …

  The limitations of Aristotle’s teachings were becoming apparent just decades after his death. It was only after scientists began rigorously applying his methods instead of his doctrines that astronomy and physics and ultimately biology would begin to turn themselves around.

  Thanks to Strato, Greek science in Alexandria bore the heavy imprint of Aristotle, and with it the future of science. All the same, there were two outstanding figures in Alexandria with undeniable Platonic roots—men who were harbingers of a still larger notion of science yet to come.

  The first was the geometer Euclid. We know almost nothing about his life. He may have been from Athens; he may even have studied at Plato’s Academy. We do know he was teaching mathematics in Alexandria about the time Strato arrived and that Ptolemy I once asked him if there wasn’t an easier way to study geometry than by taking Euclid’s classes. Euclid is supposed to have answered, “There is no royal road to geometry.” Anyone who has read his or her way through the Elements knows what he meant.

  As a textbook, Euclid’s Elements is peerless in its clarity and majesty of progression from first principles, or axioms, to particular demonstrations, or proofs. They move from the definition of line and point on the first pages to Pythagoras’s famous theorem and beyond. For more than two thousand years, they have been the model of a priori reasoning at its most dignified.

  The subtext of the Elements is also t
he principle Euclid may have absorbed from his teachers at the Academy: that mathematics and geometry are reason’s direct insight into the mind of the “supreme geometer,” God Himself. Indeed, Euclid’s principal works could almost have served as textbooks for Plato’s Rulers in the Republic. They were the Elements for arithmetic and geometry; the Conic Sections for the study of proportion and harmony; and his Phaenomena as a guide to astronomy, since it focuses on the theory of uniformly rotating spheres.13

  Still, as a work the Elements is pure Aristotle: one reason Raphael set Euclid firmly in Aristotle’s camp in his School of Athens. The book’s layout, with definitions, postulates (for instance, “All right angles are equal” and “Any line segments can be extended indefinitely in either direction”), and axioms, follows precisely the guidelines of Aristotle’s logic of science in the Prior Analytics.14

  Euclid’s aim was also the same as Aristotle’s for all science, and for all good pedagogy. Any mathematician in Alexandria in the third century BCE could point out that his Elements contained nothing new.15 What Euclid did was to set out principles that were known so clearly and elegantly that it became the most reproduced book in the ancient and medieval world, even more than the Bible.16 It remained the fundamental textbook for teaching geometry to young minds right through the nineteenth century. Minds as diverse as René Descartes, Thomas Hobbes, and Charles Darwin would get their first whiff of what scientific reasoning is all about from the pages of the Elements.

  Euclid demonstrated that geometry could not only be rigorous, but also beautiful and inspiring—a lesson the later builders of Chartres cathedral would raise to the sublime.