Full Idea
Prior things can have being without posterior things, without the posterior being able to have being without the prior, to adopt Plato's distinction.
Gist of Idea
Prior things can exist without posterior things, but not vice versa
Source
Aristotle (Metaphysics [c.324 BCE], 1019a04)
Book Reference
Aristotle: 'Metaphysics', ed/tr. Lawson-Tancred,Hugh [Penguin 1998], p.131
A Reaction
Fine quotes this, in expounding Aristotle's account of essence.