Proclus Lycius Diadochus (412–485 AD)

Proclus (Πρόκλος ὁ Λύκιος, surname Diadochus, “the Platonic Successor”) was born in Constantinople on February 8, 412 AD to Patricius and Marcella, citizens of Xanthos in Lycia, and died in Athens on April 17, 485 AD. His life is unusually well documented thanks to the biography Vita Procli (Πρόκλος ἢ περὶ εὐδαιμονίας) composed shortly after his death by his pupil and successor Marinus of Neapolis.

Education & Succession

Intended by his father for forensic rhetoric and Roman law, Proclus studied initially in Xanthus and Alexandria under Leonas and Orion, then turned decisively to philosophy after a visit to Byzantium. Studying Aristotle in Alexandria under Olympiodorus the Elder and mathematics under Heron (a devout teacher of arithmetic and geometry), Proclus sailed to Athens around 430/431 AD, aged nineteen.

At Athens he was welcomed by the aged founder of the revived Academy, Plutarch of Athens (who read Aristotle’s De Anima and Plato’s Phaedo with him), and became the closest disciple of Syrianus, whom Proclus reverently calls “our Leader” (ὁ ἡμέτερος καθηγεμών) at the close of the Euclid commentary (Friedlein 432). Upon Syrianus’s death around 437 AD, Proclus became head (Diadochus) of the Athenian Academy for nearly half a century.

Mathematical & Philosophical Corpus

Proclus united encyclopedic mastery of classical Greek science with systematic Neoplatonic metaphysics:

  • In Primum Euclidis Elementorum Librum Commentarii: His foundational treatise on philosophy of mathematics, phantasia, history of geometry, and Euclidean axiomatics.

  • Hypotyposis Astronomicarum Positionum: Critical exposition of Hipparchus’s and Ptolemy’s astronomical hypotheses and observational instruments.

  • Elementatio Physica (Στοιχείωσις φυσική) & Elementatio Theologica (Στοιχείωσις θεολογική): Demonstrative stoicheioseis applying Euclidean axiomatic-deductive form directly to Aristotelian physics (Books VI and VIII) and Platonic metaphysics.

  • Monumental Commentaries on Plato: Timaeus, Republic, Parmenides, First Alcibiades, and Cratylus, alongside Platonic Theology.