Aristotle

Aristotle (384-322 B.C.E.)

Mine is the first step and therefore a small one, though worked out with much thought and hard labor. You, my readers or hearers of my lectures, if you think I have done as much as can fairly be expected of an initial start. . . will acknowledge what I have achieved and will pardon what I have left for others to accomplish.

Aristotle was born in Stagira in north Greece, the son of Nichomachus, the court physician to the Macedonian royal family. He was trained first in medicine, and then in 367 he was sent to Athens to study philosophy with Plato. He stayed at Plato's Academy until about 347 -- the picture at the top of this page, taken from Raphael's fresco The School of Athens, shows Aristotle and Plato (Aristotle is on the. right). Though a brilliant pupil, Aristotle opposed some of Plato's teachings, and when Plato died, Aristotle was not appointed head of the Academy. After leaving Athens, Aristotle spent some time traveling, and possibly studying biology, in Asia Minor (now Turkey) and its islands. He returned to Macedonia in 338 to tutor Alexander the Great; after Alexander conquered Athens, Aristotle returned to Athens and set up a school of his own, known as the Lyceum. After Alexander's death, Athens rebelled against Macedonian rule, and Aristotle's political situation became precarious. To avoid being put to death, he fled to the island of Euboea, where he died soon after.

Aristotle is said to have written 150 philosophical treatises. The 30 that survive touch on an enormous range of philosophical problems, from biology and physics to morals to aesthetics to politics. Many, however, are thought to be "lecture notes" instead of complete, polished treatises, and a few may not be the work of Aristotle but of members of his school.

A full description of Aristotle's contributons to science and philosophy is beyond the scope of this exhibit, but a brief summary can be made: Whereas Aristotle's teacher Plato had located ultimate reality in Ideas or eternal forms, knowable only through reflection and reason, Aristotle saw ultimate reality in physical objects, knowable through experience. Objects, including organisms, were composed of a potential, their matter, and of a reality, their form; thus, a block of marble -- matter -- has the potential to assume whatever form a sculptor gives it, and a seed or embryo has the potential to grow into a living plant or animal form. In living creatures, the form was identified with the soul; plants had the lowest kinds of souls, animals had higher souls which could feel, and humans alone had rational, reasoning souls. In turn, animals could be classified by their way of life, their actions, or, most importantly, by their parts.

Though Aristotle's work in zoology was not without errors, it was the grandest biological synthesis of the time, and remained the ultimate authority for many centuries after his death. His observations on the anatomy of octopus, cuttlefish, crustaceans, and many other marine invertebrates are remarkably accurate, and could only have been made from first-hand experience with dissection. Aristotle described the embryological development of a chick; he distinguished whales and dolphins from fish; he described the chambered stomachs of ruminants and the social organization of bees; he noticed that some sharks give birth to live young -- his books on animals are filled with such observations, some of which were not confirmed until many centuries later.

Aristotle's classification of animals grouped together animals with similar characters into genera (used in a much broader sense than present-day biologists use the term) and then distinguished the species within the genera. He divided the animals into two types: those with blood, and those without blood (or at least without red blood). These distinctions correspond closely to our distinction between vertebrates and invertebrates. The blooded animals, corresponding to the vertebrates, included five genera: viviparous quadrupeds (mammals), birds, oviparous quadrupeds (reptiles and amphibians), fishes, and whales (which Aristotle did not realize were mammals). The bloodless animals were classified as cephalopods (such as the octopus); crustaceans; insects (which included the spiders, scorpions, and centipedes, in addition to what we now define as insects); shelled animals (such as most molluscs and echinoderms); and "zoophytes," or "plant-animals," which supposedly resembled plants in their form -- such as most cnidarians.