Full Idea
Philosophers have endlessly discussed and been baffled by the question 'What is that which is?' Now this question just is the question 'What is substance (ousia)?'
Gist of Idea
The baffling question of what exists is asking about the nature of substance
Source
Aristotle (Metaphysics [c.324 BCE], 1028b04)
Book Reference
Aristotle: 'Metaphysics', ed/tr. Lawson-Tancred,Hugh [Penguin 1998], p.168
A Reaction
Vasilis Politis says 'ousia' is 'primary being'. 'Substance' is a theory about the nature of primary being.