The Catholic World. Vol. XIX., No. 109.—April, 1874.

The Principles Of Real Being. IV. Intrinsic Principles of Substance and Suppositum.

We have briefly shown in the preceding article that a complete being, to be a substance and a suppositum, requires no positive addition to its three intrinsic principles, but needs only to be left to itself. This is, in our opinion, an obvious truth. But as there are philosophers of high repute who do not fully share the same opinion, and, on the other hand, the notions of substance and of suppositum are both intimately connected with some theological truths which cannot be well explained without a distinct knowledge of what these two notions really imply, we deem it expedient to enter into a closer examination of the subject, that we may better understand by the light of reason, and confirm by the weight of authority, the traditional doctrine on substance and suppositum, their essential constitution, formal distinction, and supernatural separability.

Substance is very commonly described as “that which is in itself and by itself”—quod in se et per se subsistit. This definition exhibits the “predicamental” substance—that is, a substance ultimately complete, which is at the same time a suppositum also, according to Aristotle's comprehensive conception of substance. And it is for this reason that such a definition is made up of two members; of which the first—viz., “that which exists in itself”—strictly applies to substance as such; whilst the second—viz., “that which subsists by itself”—strictly refers to the suppositum as such, and exhibits substance as possessing its own natural subsistence or suppositality.

Philosophers, when speaking of things as existing in their natural state and condition, are wont to say indiscriminately that substance is a being which “exists in itself,” or a being which “subsists by itself.” [pg 002] This they can do without any danger of error so long as they keep within the bounds of pure nature; since, in the natural order, anything that exists in itself subsists by itself, and vice versa. But natural things can, by supernatural interference, be raised to a mode of existence transcending their natural condition, as we know by divine revelation; and in such a case, the mode of substance and the mode of the suppositum must be, and accordingly are, most carefully distinguished from one another. Thus we know by faith that in Christ our Lord there is the true substance of a human body and of a human soul; and nevertheless we know that his human nature does not subsist by itself, but by the Divine Person of the Word. The obvious inference is that a nature which exists in itself does not necessarily subsist by itself; in other terms, the formality of substance and the formality of the suppositum are entirely distinct from one another, and the one can remain without the other. “What makes substance to be essentially a substance,” as Suarez remarks, “is not its subsisting actually by itself, but its having an essence to which subsistence is naturally due—viz., an essence which is of itself a sufficient principle of subsistence.”[1] From this we learn that the words per se esse, or “to subsist by itself,” are inserted in the definition of substance, not to show what substance as such is, but only to point out what is naturally due to substance—viz., what accompanies it in its natural mode of existing. Substance as such would therefore be sufficiently characterized by the words, “that which is in itself.”