I use the term “essence” a lot, and I sorta regret/sorta don’t regret doing that because it does oversimplify issues. It also provides a good-enough introduction to thinking without getting lost in too much jargon or too many distinctions. I throw plenty of those at you.
Nonetheless, I should have posted this earlier, from Joe Sachs’ translation of On the Soul by Aristotle, p. 203:
what it is for something to be (ti en einai) What anything keeps on being, in order to be at all. The phrase expands ti esti, what something is, the generalized answer to the question Socrates asks about anything important: “What is it?” Aristotle replaces the bare “is” with a progressive form (in the past, but with no temporal sense, since only in the past tense can the progressive aspect be made unambiguous) plus an infinitive of purpose. The progressive signifies the continuity of being-at-work [energeia, activity/”kinetic energy”], while the infinitive signifies the being-something or independence that is thereby achieved. The progressive rules out what is transitory in a thing, and therefore not necessary to it; the infinitive rules out what is partial or universal in a thing, and therefore not sufficient to make it be. The learned word “essence” contains nothing of Aristotle’s simplicity or power.
If you can make head or tail of that, congratulations, you’re the world’s smartest person and eligible for a PhD. at any number of fine schools. For now, just go back anytime I used the word “essence,” read all that in, and fix the arguments to make everything kosher, k?