|The real distinction is real if we mean by it
that essence does not mean the same thing as existence, that what things are is not the
same as that they are, that the being of creatures is not the same as the being of God.
But the real distinction is not real is we mean by it essences somehow exist before they really exist, that reality is divided into two real orders that we call essence and existence, that essence is not ultimately reducible to existence.
The challenge of metaphysics is do carry out this reduction of essence to existence in such a way that the ultimate ontological structure of essence is revealed. A truely existential thomism needs to see essence in the light of existence or in the light of what we could call the intuition of being.
An essence is this or that capacity for existence. It is, we could say, a real capacity or real potency for existence. But we could also say that essences dont exist outside of their capacity for existence. Existence itself, which is the metaphysical name of God, can express itself by creating this or that particular existing thing. God creates limited existences and essences are our mind appreciation of these particular forms of existence.
We could say that without essences created things could not exist, but this is to put things backwards. God does not create essences and then make them exist. God creates existing things and we see that they are various colors or flavors or modes of existence. But in this seeing we tend to leave aside existence and focus on the different modes and forget they are modes of something, modes of existence. Essences as they actually exist are identical to the modes of existence.