Of God and His Creatures

In whatever reality essence and existence are identical, that reality is its own existence: in other words, it exists of itself, which self-existence is proper to God alone. That is the whole argument of this chapter. All scholastic writers agree in admitting some sort of distinction between essence and existence in creatures: but as to the nature of that distinction as it obtains in existing creatures, and the name by which the distinction should he expressed, there has been fierce contention between the later Thomists and other schools. Non nostrum inter vos tantas componere lites.

Of God and His Creatures: 2.52