The condition in which a thing is acting out of its own inner nature. God alone is supposed to be describable as per se esse, that is, existing out of his or her own inner necessity. It was a doctrine of Aquinas that ‘quod est per se, semper est prius eo quod est per aliud’: that which is per se is always prior to that which depends upon something else. The notion forms the background to the cosmological and ontological arguments.
Philosophy dictionary. Academic. 2011.