is here defective,
precisely because what is simple and one, can only be represented by
divers things; consequently, composition is accidental to them, and
therefore, in them _suppositum_ is not the same as nature.
_______________________

FOURTH ARTICLE [I, Q. 3, Art. 4]

Whether Essence and Existence Are the Same in God?

Objection 1: It seems that essence and existence are not the same in
God. For if it be so, then the divine being has nothing added to it.
Now being to which no addition is made is universal being which is
predicated of all things. Therefore it follows that God is being in
general which can be predicated of everything. But this is false: "For
men gave the incommunicable name to stones and wood" (Wis. 14:21).
Therefore God's existence is not His essence.

Obj. 2: Further, we can know _whether_ God exists as said above
(Q. 2, A. 2); but we cannot know _what_ He is. Therefore God's
existence is not the same as His essence--that is, as His quiddity or
nature.

_On the contrary,_ Hilary says (Trin. vii): "In God existence is not an
accidental quality, but subsisting truth." Therefore what subsists in
God is His existence.

_I answer that,_ God is not only His own essence, as shown in the
preceding article, but also His own existence. This may be shown in
several ways. First, whatever a thing has besides its essence must be
caused either by the constituent principles of that essence (like a
property that necessarily accompanies the species--as the faculty of
laughing is proper to a man--and is caused by the constituent
principles of the species), or by some exterior agent--as heat is
caused in water by fire. Therefore, if the existence of a thing
differs from its essence, this existence must be caused either by some
exterior agent or by its essential principles. Now it is impossible
for a thing's existence to be caused by its essential constituent
principles, for nothing can be the sufficient cause of its own
existence, if its existence is caused. Therefore that thing, whose
existence differs from its essence, must have its existence caused by
another. But this cannot be true of God; because we call God the first
efficient cause. Therefore it is impossible that in God His existence
should differ from His essence. Secondly, existence is that which
makes every form or nature actual; for goodness and humanity are
spoken of as actual, only because they are spoken of as existing.
Therefore existence mus