Only God is being by essence: existence is of the divine essence, not of the creature

Article II. The second division of real being is proposed, and it is proved that God alone is being by essence.

This division is into being by essence and being by participation. Being by essence is the glorious God, who exists by the force of his own essence. Beings by participation are created beings, which have no actual and real existence in the world except as communicated and participated from another by whom they were produced — that is, from God. But that it may be understood how God is said to exist by the force of his essence, let these foundations be held.

First: the existence of God is of his essence. That is, it is not something superadded to the divine essence, nor ought it to be conceived by us as something superadded to it, but it is something included in the very essence of God, no less than animality or rationality is enclosed in human essence. This is shown thus: every substantial perfection is of the essence of God (for the essence of God would not be of infinite perfection if some perfection were granted which his essence does not enclose in itself); but existence is a substantial perfection, as is plain to anyone; therefore it is of the essence of God. Just as, therefore, it is of the essence of a human being to be an animal, or a body, or a substance, so it is of the essence of God to be something actually existing.

2. On the contrary, it is neither necessary nor possible that the existence of a creature be of its essence. It is not necessary, because the essence of a creature is not of infinite perfection. It is not possible, because whatever is of the essence of a thing necessarily belongs to that thing, and its affirmation of that thing is necessary and of eternal truth. But existence does not stand thus in creatures: for I do not truly say, it is necessary that a rose exist, or it is necessary that thunder exist — for they can fail to exist. Yet I do truly say, it is necessary that a rose be a flower, or that thunder be a sound, even when rose and thunder do not exist. Hence it is plain that these latter are essential predications, but not those former. This reason proves not only that existence is not of the essence of a creature, but also that existence does not necessarily follow the essence of a creature or flow from it. For whatever is essential by flowing forth is necessarily affirmed of the thing to which it is essential; but actual existence (as has been said) belongs to creatures contingently. Meanwhile we admit that the capacity or potency for existence belongs not contingently but necessarily and essentially to every real being, whether created or uncreated; but the same is not to be said of actual existence.

3. Let the second foundation be this. If anyone asks whence it is that God exists and cannot fail to exist, no reason can be given except this one: namely, because his essence is of infinite perfection — that is, it encloses every perfection in itself, and therefore existence also. Hence it is plain that God is rightly said to exist by the force of his essence. But if the question is moved concerning creatures — whence it is that they now actually exist — one must not answer that this happens because such is their essence, or because that is the condition of their essence; for their essence is indifferent to existing and not existing — that is, it can exist or not exist at the will of God. Rather one must answer that the true reason of that fact is that their essence, which earlier was only possible and apt for existing, has now been given the very act of existence by God and by secondary causes. Creatures therefore cannot be said to exist by the force of their essence, but by the force of the causes from which they were produced, and chiefly of the first cause. Hence it follows that they are not beings by their own essence, but by participation and reception of existence from the first cause. Besides, the reason of this matter can be given from this very clear foundation: it is the condition of the divine essence that it cannot fail to exist, and that it cannot participate its existence from another; but it is the condition of a created essence that it can, at the will of the first cause, have existence or not have it, and that it cannot exist except by participating the act of existence from the first cause. Hence it is plain that the first cause exists by the force of its essence; but secondary causes, or created beings, do not exist by the force of their essence, but through the action of the first cause from which they receive actual existence.

4. Third foundation. The essence of a creature is rightly and truly called potency; but the existence of a creature may well be called an act superadded to the essence. This is declared thus: just as physical matter is called potency and physical form act, because matter in itself and from itself has no form, but is capable of form, or can receive form, so the essence of a creature can be called potency, because it neither encloses existence in itself nor has it from itself, but is capable of it, or can receive it and participate it from the first cause. But on the contrary the essence of God stands far otherwise: for in itself it encloses the act of existing; and therefore it does not stand toward existence as potency toward act — for no potency encloses act in itself, but is referred to act as to something external. And so much concerning the division of being into finite and infinite.