Proclus Diadochus

410-485

Byzantine Philosopher

The life and career of Proclus represent both a summing-up of classical Greek mathematics, and a throwback to a time—already ancient in Proclus's era—when Greek mathematical study was at its zenith. It is thanks to his writing, particularly a commentary on Euclid's Elements, that modern scholars know of many long-lost works of antiquity.

Son of a prominent couple named Patricius and Marcella, Proclus grew up in the town of Xanthus on the southern coast of Lycia in Asia Minor (modern Turkey). His father intended him to study law in Alexandria, but on a visit to the capital of the Eastern Roman Empire at Byzantium or Constantinople (now Istanbul), he decided instead to pursue a career as a philosopher.

By that point Proclus had already been pursuing his legal education in Egypt, but he returned to Alexandria with an entirely different aim. Over the years, he studied with Leonas of Isauria, a Sophist; the Egyptian grammarian Orion; the philosopher Olympiodorus the Elder; various instructors in Latin and rhetoric; and a mathematician named Heron, though not the better-known figure who went by that name.

Eventually he decided to go to Athens to pursue the study of neo-Platonic philosophy in the Academy established by Plato (427-347 b.c.) himself. (In the sixth century the Byzantine emperor Justinian closed down the Academy, by then some 900 years old, as a pagan institution.) At the Academy he studied under Plutarch of Athens, founder of the Athenian school of Neoplatonism and director of the Academy, as well as Plutarch's successor Syrianus. When the latter stepped down, he named Proclus head of the Academy, and it was around this time that the scholar acquired the title Diadochus, meaning "successor."

In the years that followed, Proclus wrote a variety of works, none more important than his commentary on the Elements of Euclid (c. 325-c. 250 b.c.). Euclid's work is valuable in a number of regards, but perhaps most of all for the fact that it constitutes the principal source of information regarding mathematicians and works that would otherwise have long been forgotten. Also of interest to the history of science was Hypotyposis, an overview of astronomical theories put forth by Hipparchus (fl. 146-127 b.c.) and Ptolemy (c. 100-170). Works on physics include Liber de causis or "Book of causes" and Elements of Physics, which discusses ideas put forward by Aristotle (384-322 b.c.).

Proclus also wrote books of poetry and theology. His poetry was quite good, and the seven of his poems that survive are acclaimed as examples of an accomplished late-classical style. These poems are mostly hymns to the gods, an interesting fact because by his time, Christianity had triumphed throughout both the Eastern and Western empires. Yet Proclus remained unabashedly pagan, and his writings on religion concerned not Jesus Christ, but the gods of Greece and the Orient.

In many regards Proclus seemed to recall the ways of the mathematicians who followed the school of Pythagoras (c. 580-c. 500 b.c.). Like them he was a vegetarian, and he mixed with his scientific study heavy doses of superstition and bizarre beliefs that had nothing to do with science. (For instance, he maintained that Earth is the center of the universe because a Chaldean priest of old had said so.)

He also practiced magic, and though these tendencies might seem a harbinger of the medieval period that followed his time, in Proclus's case they can more accurately be seen as harkening to the Pythagorean past. Greece, after all, never experienced a medieval dark age; instead it simply preserved the advanced learning of the past, without adding a great deal to it, as a dusty relic of antiquity. Much the same was true of Proclus, who is remembered not for his original contributions, but for the manner in which he summed up the mathematical and scientific knowledge acquired during the energetic millennium that preceded his own time.

JUDSON KNIGHT