I don’t usually give this question much thought as i do not think that a proof for God’s existence requires this question to be answered.
I think, in general, on some level there is such a thing as what things are in comparison to other things. Otherwise there couldn’t possibly be any diversity; everything would be the same. There could be no true distinctions. That’s a common sense argument.
Also, while it is true that putting bricks together to build a wall does not actually result in an actual nature that is a wall, i think it is self evident that there are beings where the whole is dependent on it’s composition but nevertheless the whole possesses a nature that is greater than and cannot be reduced to its parts, insomuch as none of the parts possesses what the whole has. I think this is real and a reasonable conclusion based on our experiences.
For the sake of moving Thomism forward into today’s world with all the scientific advances in physics, I would like someone to provide some proofs for the existence of essences.
Is there really such a thing as having the essence of a cat?