Full Idea
We have knowledge of each thing when we grasp the what-it-was-to-be [to ti en einai] that thing.
Gist of Idea
We know a thing when we grasp its essence
Source
Aristotle (Metaphysics [c.324 BCE], 1031b08)
Book Reference
Aristotle: 'Metaphysics', ed/tr. Lawson-Tancred,Hugh [Penguin 1998], p.186
A Reaction
This is a key remark in my understanding of the whole business of essentialism. It really concerns the way in which we are able to grasp reality, rather than how it is in itself. It is not mere convention, because the grasping responds to the reality.