Entry 0046: Commentary On
De veritate, question 1, article 1, corpus
The text establishes a clear demarcation between the term derived from the metaphysical principle of essence and the term derived from the metaphysical principle of actus essendi. Among other things, the text illustrates the meaning of the transcendental notion of res (thing), a term which derives its content and its transcendental connotation from the quiddity or essence of the thing.
The underlying principle of this doctrine is that, in the real world, one cannot have one of these two metaphysical principles existing without the other being present. In the real world essences exist with the actus essendi, and vice versa, the actus essendi always appears instantiated in an essence. For this reason, the term res (thing) expresses a transcendental notion; it stands for a universal mode of being that follows upon the fact of having an essence. Essences are found in every existing thing without exception.
Thus, from the side of the actus essendi every existing thing is said to be ens and from the side of the essence every existing thing is said to be res.