Where does the essence of things come from?
On the axis: Essence and existence · the essence of things
If things have an essence, where do they get it: from a plan that conceives them before they exist, from nature itself, from a convention of our minds, or from nothing?
Justification
For a manufactured object, the paper-knife, essence (the artisan's concept) precedes existence; tradition thought of man likewise, created according to a human nature conceived by God. Remove the creator, and the order reverses for man alone: he exists first, with no prior definition, and it is from being nothing at the outset that he draws the full responsibility of making himself.
Man first exists, encounters himself, surges up in the world, and defines himself afterward. If man as the existentialist conceives him is indefinable, it is because at first he is nothing. He will not be anything until later, and then he will be what he makes of himself.Existentialism Is a Humanism
Existentialism Is a Humanism (1946) · Being and Nothingness, Introduction and Part 1 (the for-itself)
Justification
Aristotle turns 's own demand for essence against him: if the essence of a thing is what makes it what it is, lodging it in a separate world of makes it unable to explain the sensible thing, from which it is then cut off. The form must therefore be in the individual, as the soul is in the body: every sensible substance is a compound of matter and form, . Essence is no longer a celestial model but the what-it-was-to-be, what the thing is in itself, grasped in the definition, without thereby denying that form is the most real and most knowable thing in it.
Metaphysics, VII (Zeta).4 and 17
Justification
Against Plato, Aristotle rejects separate Forms: the universal is real, but it exists only within individuals, as their form. The form of the horse does not exist apart from singular horses, yet it is genuinely real in them. This is an immanent realism.
Metaphysics, Z; Categories, 5
leads to: Universals