MATHEMATICIAN, ASTRONOMER

Life
Neoplatonist philosopher, mathematician and astronomer, Proclus was born in Constantinople and reared in Xanthus, in Lycia. After an early education in Xanthus and Alexandria, under Orion Leonas, Hero (mathematics) and Heliodorus (Aristotelian philosophy), he went to Athens. There he studied with Plutarch of Athens and his disciple Syrianus (Platonic philosophy), eventually succeeding the latter as the head of the Academy. He was influenced by the philosophy of the Pythagoreans, and in turn influenced many Western philosophers: Hegel, for example, admired him greatly. He died in Athens in 485. One of the craters on the moon has been named "Proclus" in his honour.


Work
His principal writings are:

"Hypotheses in astronomy": Treatise on the systems of Hipparchus, Aristarchus and Ptolemy. This work is divided into five parts:

A) Description of the method of calculating the apparent diameter of the sun by the use of Hero's water clock and the information provided by Pappus.

B) Proof of the geometric equivalence of epicycles and eccentrics.

C) Description of an annular eclipse of the sun, based on the account of Sosigenes the Peripatetic.

D) Relation of the evolution of the equinox.

E) Hypotheses on the distances between the planets.

"On the sphere": Treatise on the celestial spheres with reference to Geminus.

"Paraphrase of the four books of Ptolemy "

"Commentary on Euclid": This book is invaluable for the study of ancient Greek geometry, for it includes elements from lost works by Eudemus (4th century BC) and Geminus (c. 70 BC).

"On the results of lunar and solar eclipses "

"Elements of Physics": Commentary on Aristotle's theory of motion. Analytical commentary on the work of Hesiod, Plato and Aristotle.