Aristotle’s writings, although less elegant than Plato’s, were more systematic. Ultimately, he also diverged from Plato with regard to politics. While his aristocratic, conservative teacher condemnedAthens’ extreme form of democracy, Aristotle, more a man of the people, cautiously approved of the Athenians’ progressive idea of rule through majority decision-making. Aristotle eventually departed Athens, accompanied by his friends Theophrastus (the future “father of botany”) and Xenocrates. They sailed northeast to Assos, where Aristotle assumed the leadership of a circle of philosophers assembled there by another old Academy friend, Hermias of Atarneus, now the city’s ruler. Aristotle spent the next four years — first at Assos, then on the island of Lesbos across the water — conducting fundamentalscientific research, especially in zoology and biology, which remained unsurpassed for the next two millennia. His extraordinary powers of observation, together with those of the fishermen and other sharp-eyed informants or collaborators he relied on, led to the classification of more than 500 (often minutely described) species.Two intriguing creatures that Aristotle closely documented were theoctopus and the Black Goby, a small fish local to Lesbos and surrounding waters. The investigator’s description of the octopus’ lengthy, vine-like, sperm-delivering hectocotyl arm and his accurate suppositions about the male goby’s highly peculiar mating habits and secondary sexual characteristics were long considered incredible and had to wait until the 19th and 20th centuries to be confirmed by modern science.

A ROYAL TUTOR

In Pella, the boy who would become Alexander the Great was reaching adolescence, and his father must have decided that Aristotle would be useful in shaping his son’s young mind. The philosopher was summoned to the Macedonian capital in 343 BC, where he took overAlexander’s education, tutoring him (and, if tradition holds true), other prominent sons at the shady, riverside cave complex at Mieza. A small L-shaped stoa (colonnaded, roofed walkway) once stood against the cliff face at the picturesque rural site (Veria-Naoussa-Edessa region), known today as the School of Aristotle. Aristotle fed Alexander’s omnivorous curiosity for knowledge, giving him instruction in Homeric literature, philosophy, morals, religion, logic, art, geometry, astronomy, rhetoric and medicine. The future king’s appreciation for learning was apparent again after 334 BC, when, on his Asian campaign, he included in his entourage a team of zoologists, botanists and other scientists. Prior to his departure for Persia, Alexander seems to have found another role for Aristotle, sending him back to Athens in 335 BC to establish a rival school of philosophy: theLyceum. Over the next dozen years, Aristotle lectured repeatedly on a vast range of subjects – augmented and refined since his last tenure in Athens – including astronomy, biology, botany, chemistry, ethics, history, logic, metaphysics, meteorology, philosophy of mind, philosophy of science, physics, poetics, political theory, psychology, rhetoric and zoology. While is old alma mater the Academy maintained a relatively narrow scope, the Lyceum offered a broader view – more like a modern “university” – focusing especially on Aristotle’s favorite pursuit: the detailed examination of nature.

DEATH AND LEGACY

After Alexander’s demise in 323 BC, Athens again became uncomfortable for Aristotle. The following year, with the example of Socrates in mind, he is said to have departed the city at his own choosing, wishing to save Athens from twice sinning against philosophy. He retired to Chalcis, where he soon passed away at age 62 from a stomach ailment – leaving all his papers and his vast scholarly library to Theophrastus, his successor at the Lyceum. Eventually, when Athens was overrun and looted in 86 BC by the Roman general Sulla, Aristotle’s writings were carried back to Rome, where, in 60 BC, they received their first collation, titles and commentary from Andronicus of Rhodes. Aristotle’s surviving works, although perhaps only one-fifth of his total output, still amount to about one million words; the most important texts include Physics, Metaphysics, Nicomachean Ethics, Politics, De Anima (On the Soul) and Poetics.

Aristotle also invented the field of logic (“analytics”), pioneered zoology – both observational and theoretical – and systematically defined many other academic disciplines. He divided the sciences into three categories: productive (those offering products, such as engineering, architecture and rhetoric); practical (those guiding behavior, such as ethics and politics); and theoretical (those seeking information and understanding for their own sake, such as pure mathematics and what we know today as philosophy). Aristotle believed science must be approached logically. He demonstrated inductive and deductive reasoning in his now-famous syllogism: “A = B, B = C, A = C” or, as he also put it, “Every Greek is human; every human is mortal; therefore, every Greek is mortal.” He disagreed with Plato that application of reason was most important, instead suggesting a scientific methodwithin which both logic and especially observation are essential. In this way, he fostered the birth of empirical science.