Proclus (412–485 CE): key ideas and works

Proclus was born in Constantinople in 412 to a wealthy family from Xanthos in Lycia, where he grew up. He went to Alexandria to study rhetoric and become a lawyer like his father, but turned to philosophy, learning Aristotle’s logical works by heart. At eighteen he moved to Athens to study at the Platonic school under Plutarch of Athens and then Syrianus, whom he succeeded as head in 437. He led the school for nearly half a century and died in 485. His pupil Marinus describes a disciplined life of lectures, writing and prayer, and his practice of theurgy, pagan ritual that had to be kept within the school’s walls in a Christian city.

He wrote around 700 lines a day, and about a third of his output survives: commentaries on Plato and Euclid, systematic works and hymns. He accepted Plotinus’ three levels of reality, the One, Intellect and Soul, while criticising Plotinus on several points, and he aimed to show that Homer, the Orphic poems and the Chaldaean Oracles agreed with Pythagoras and Plato. His influence on the Middle Ages was mostly indirect: the Christian writer known as Dionysius the Areopagite drew heavily on his works, and the Book of Causes, an Arabic adaptation of the Elements of Theology, circulated under Aristotle’s name until Thomas Aquinas identified its source. Nicholas of Cusa and Marsilio Ficino read him closely.

Key ideas

A system in propositions

The Elements of Theology sets out Neoplatonic metaphysics as 217 linked propositions, each proved from the ones before. The first half establishes the One, unity with no multiplicity at all, as the ultimate cause of everything; the second deals with gods, intellects and souls.

Remaining, proceeding, returning

Each effect stays within its cause, goes out from it and returns to it. Without proceeding it would be identical with its cause; without remaining it would have no bond with it. This pattern of three repeats at every level of reality.

The henads

Between the One and the level of being he placed the gods, which he called henads, or “unities”. This let him fit the gods of Greek religion into a philosophical account of first principles, a “scientific theology”.

True causes stand above their effects

Matter and form, which exist inside the things they make up, are only auxiliary causes, or instruments. Causes in the full sense act on their effects from outside and transcend them, as Plato’s Forms and divine craftsman do.

Foreknowledge and free choice

How we know something depends on the knower, not the thing known. So the gods know contingent events in a way that is not contingent, and timelessly know what happens in time, without taking away human choice. Boethius later took up this answer.

Influences

Where these links come from

Proclus drew on Plato. Source: Christoph Helmig and Carlos Steel, Proclus, Stanford Encyclopedia of Philosophy
Proclus drew on and argued against Aristotle. Source: Christoph Helmig and Carlos Steel, Proclus, Stanford Encyclopedia of Philosophy
Proclus drew on and argued against Plotinus. Source: Christoph Helmig and Carlos Steel, Proclus, Stanford Encyclopedia of Philosophy
Boethius drew on Proclus. Source: Christoph Helmig and Carlos Steel, Proclus, Stanford Encyclopedia of Philosophy
Meister Eckhart drew on Proclus. Source: Amber L. Griffioen, Meister Eckhart, Stanford Encyclopedia of Philosophy
Nicholas of Cusa drew on Proclus. Source: Clyde Lee Miller, Cusanus, Nicolaus [Nicolas of Cusa], Stanford Encyclopedia of Philosophy

Proclus

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