Gift and the Unity of Being. Antonio López M.

pephukos),” as “that to whose quiddity it belongs not to exist in another.”115 With this distinction, Aquinas is not rejecting the conception of substance as “to be in itself.” He is rather indicating that a created singular stands in itself (per se, kath’auto) not so much because it is the source of its own existence—this would be the case if esse were an accident of essence—but because it is given to it to be. Thus, for Aquinas, the definition of substance must include the essence (quiddity) and not only esse as in Aristotle (to be by nature self-subsistent).