Thinker · Aristotelians
Avicenna
980 – 1037 · Aristotelians · Faith meets reason
Between Aristotle and the moderns, no one built a bigger system than Ibn Sina. He took the whole of Aristotle, fused it with the Neoplatonic picture of a world flowing out of the One, and set at the center of metaphysics a single distinction the Greeks had never made load-bearing: that what a thing IS and THAT it is are two different facts. From that one cut he drew the existence of God, a direct proof that the self knows itself without the body, and a chain of being that runs from a necessary source down to every passing thing. Latin Europe read him for centuries, and when [Aquinas](/philosophy/thinker/aquinas) reached for the tools to prove God by reason, half of them were Avicenna's.
What changed
Before
Aristotle hands down a logic of substances; existence is just assumed
After
Existence itself becomes the question, and it splits from essence
Inside the walk-through
The boy who read the library
The two great books
The flying man
What a thing is, that a thing is
The Necessary Existent
The chain of being, and the long afterlife