This chapter follows naturally on the preceding; for the analysis of being into act and potency points clearly to the still more radical and precise analysis of it under the terms of essenec and existence. The chapter envisages a conclusion of paramount importance; in Cajetan's estimation, "the ultimate foundation of all St. Thomas" (maximum fundamentum doctrinae Sancti Thomae).1 The conclusion: In created being the principles of essence and existence differ by a real distinction.
That being has both the aspect of essence and existence is as much as admitted by everyone; it could hardly be otherwise, for these aspects are primary data for the intellect and inseparable from the very notion of being. After all, being comes to us precisely as "that which is," in other words, as something, an <em>essence</em>, endowed with the significant trait of being or existing. Eliminate one or the other from the notion of being, and the notion itself is eliminated.
Granted this, we have still to explain in detail how essence and existence stand to each other, their respective function in the formation of being, their contribution to its structure. More specifically, the problem under consideration is the distinction of essence and existence, about which there are, in the main, two schools of thought: those who deny the real distinction, and those who affirm it.
If the real distinction is denied, being has no real composition, no structural differentiation; it will be much like a solid rock, all of a piece. To speak of essence and existence is then mostly just that, a manner of speech, having only subjective value; for the distinction, even if granted some foundation in reality, would not exist as such in reality but only in the mind conceiving it. If, on the other hand, essence and existence are taken as distinct ontological principles, then the ultimate structure of being comes out as a composition of the two. In this case the distinction of essence and existence is of course real, yet not so as to render them independent existents. It cannot be said too often that this is not a distinction of things having existence before composition - which makes no sense at all - but of interdependent principles that constitute but one and the same being.
Philosophically speaking, the problem of essence and existence arises out of the formal multiplication and limitation of created beings and, secondarily, out of the relation of these to uncreated being, unique and infinite. Beings, as we know them, are many and limited. But whence this limitation and multiplication, it being understood there must be an intrinsic as well as an extrinsic principle of limitation? The answer, for material beings, we touched on in connection with the individuation of material substance. Material beings, we noted, are composed of matter and form. Matter receives form and in receiving limits it and makes possible its multiplication.
This solution will not do, however, when it comes to the multiplicity of pure forms, such as, for St. Thomas and Thomists generally, the angelic substances. Devoid of matter, they have obviously to be limited and multiplied through something else. Which raises the question whether such beings do not bear composition of another kind to account for their limitation and multiplication. And the answer, it turns out, is yes, the composition of essence and existence. Furthermore, considering limited beings in their relation to uncreated and unlimited being, we may well ask how it is that the former retain their individual identity instead of being lost in pantheistic unity with the one primary being. Clearly, between limited beings and the infinite being with its utter simplicity there must be a difference of structure; and since the one is all simplicity, the others, it would appear, must harbor complexity.2