But a compound of the kind just mentioned is sometimes intended for an end which cannot be attained without the concurrence of a higher principle. Then, by the introduction of this new principle, a second kind of substantial compound arises, in which one of the components (the higher principle) ranks as the formal, and the others as the material, constituent of the compound nature. Such is the case with our own bodies; which, to fulfil the ends for which they are organized by nature, besides their bodily constitution and organism, require the infusion of a distinct principle of life. Hence the formal constituent of man, and of all animals too, is the principle of life, or the soul; whilst his material constituent is the body, with its organic constitution.
That the body is a physical being and a substance there is no doubt; and that the soul also is a physical being and a substance distinct from the body is conclusively shown in all good treatises of anthropology. The soul and the body are therefore two physical components, and make up a physical compound. The animal life, however, which is the result of the animation of the body by the soul—and is, therefore, the complement of the compound—is not a third physical component, but a metaphysical entity; and thus of the three principles which constitute the animal, the first and the second only are to be reckoned as physical parts.
And now, since we have stated that the constituents of compound natures may have either a physical or only a metaphysical entity, we must further inform our readers that a great number of authors are wont to consider all the real constituents of physical beings as so many physical entities. But we would say that in this they are mistaken; for although it is evidently true that the constituent principles of a physical [pg 176] being have a physical existence in the being to which they belong, it cannot be inferred that therefore all such principles must be called physical beings; as some of them can neither have an independent existence nor be even conceived without referring to their correlative principles. Thus the act and the term of a primitive being are both entitatively less than physical beings; for the first being we find in the physical order is that which arises out of them. It is not, therefore, the same thing to say that a being is physically real, and to say that it is made up of physical realities. The first assertion may be true, and the second false; because a thing which is one has only one existence, and nevertheless implies three principles; whence it appears that it is impossible to conceive each of the three principles as having a distinct existence. And since that which has no distinct existence in nature is not a physical being, accordingly the principles of primitive physical beings are not physical, but only metaphysical, realities.
We have further to remark that the act and the term, even when they are complete physical entities, in their manner of principiating the compound nature always behave towards one another as incomplete entities, inasmuch as their principiation is always of a metaphysical, and never of a physical, character. To speak first of those compound essences whose form is composition, we observe that the physical components of such essences are indeed in act, absolutely speaking, but, with regard to the composition, they are simply in potency: and since it is in this last capacity that they enter into the constitution of the compound nature, it is evident that they contribute to its constitution only inasmuch as they have a claim to further actuation. For to be potential respecting any kind of composition means not only that the parts might be duly disposed to undergo such a composition, but moreover that they are already disposed and related to each other in that manner which imperatively calls for such a composition. Consequently, the components, when thus disposed, constitute a potency which needs actuation, and stands, with respect to the form of composition, in the same relation in which any term stands with respect to its essential act. It is, therefore, manifest that the said components, though they are physical entities, behave as metaphysical principles in their material principiation of a compound essence. As for the composition itself, we have already seen that it is always a metaphysical constituent.
In the same manner, the soul and the body are indeed physical beings, absolutely speaking, and, therefore, independent of one another so far as their existence is concerned; but the body is informed and vivified, not inasmuch as it exists in its absolute actuality, but inasmuch as it is potential respecting animal life—that is, inasmuch as its organic composition imperatively claims a soul. And similarly the soul is a vivifying form, not inasmuch as it is something absolute in nature, but inasmuch as it naturally requires completion in the body for which it is created and to which it is actually terminated. It therefore appears that the soul and the body, in their principiation of the animal, behave towards one another as metaphysical principles.
Hence all composition of act and potency is, properly speaking, a metaphysical composition; though, when the compound is resolvable into physical parts, the same composition may also, from the physical nature of the components, be rightly styled physical. The difference between a metaphysical and a physical compound does not, therefore, consist in the character of the composition itself, which is always metaphysical, but in this: that the latter can be resolved into physical parts which may and will exist after their separation, whereas the former can be resolved only into metaphysical constituents which are utterly incapable of separate existence.
What precedes refers to the immediate constituents of compound essences. It is evident that every immediate principle, which is a complete being, involves other principles. Hence all compound essences imply some principles which are proximate, and others which are remote. The remote are those by which every primitive component is itself constituted in its individual reality, and from which the components derive their real aptitude to become the material, the formal, or the efficient principle of the compound essence.
Principles of accidental compounds.
We have hitherto shown that all physical beings, whether physically simple or physically complex, involve in their constitution an act, a term, and a formal complement. Nothing more is required to conclude that no physical being can be conceived of as an act without its term, or a term without its act, or a formal actuality not resulting from the concurrence of an act and its suitable term. From this it immediately appears that accidents and accidental modes are not physical beings, and that their existence is necessarily dependent on the existence of some other thing of which they are the appurtenances.