Proclus
Greek Neoplatonist philosopher (412–485 AD), born in Constantinople into a family of Roman administrative officials of Lycian origin, trained in Alexandria and finally in Athens, where he succeeded Syrianus as head of the Platonic Academy, the very institution founded by Plato eight centuries earlier, exercising there for nearly fifty years an intellectual authority so great that he earned the epithet 'Diadochus' ('the Successor'). A strict vegetarian, ascetic and deeply religious, he combined the most systematic philosophical rigour with intense practice of theurgy — mystical rituals of Chaldean ancestry aimed at establishing contact with the divine — in a synthesis characteristic of late Neoplatonism, which sought not only to understand the cosmos intellectually but also, and above all, to return the soul to it through ritual practices. His most influential work, the Elements of Theology, presented with a rigorous geometric structure explicitly inspired by Euclid's Elements — two hundred and eleven propositions, each logically deduced from the preceding ones — exhaustively systematises Neoplatonic metaphysics: it describes a cosmic hierarchy emanating from the absolute One, passing through a complex series of henads (divine units), Intellect, Soul and finally matter, each of these spheres reflecting and participating in those above in a meticulously detailed web of correspondences. He also wrote extensive commentaries on Plato's dialogues (Timaeus, Parmenides, Republic), which constitute fundamental sources for understanding the Neoplatonic interpretation of Plato, and treatises on mathematics and astronomy. His systematic synthesis exerted a decisive influence, through medieval Arabic and Latin translations — including the famous Liber de causis, mistakenly attributed to Aristotle for centuries — on both Islamic philosophy and Christian scholasticism, including Thomas Aquinas.