Furthermore, an accident needs a substance not formally qua substance, or as a mode of being naturally existing in itself; it needs a substance as a subject in which to inhere, which it will in some way affect, determine, qualify; but the subject in which it immediately inheres need not always be a substance: it may be some other accident, in which case both of course will naturally require some substance as their ultimate basis.
Comparing now the concept of accident with that of substance, we find that the latter is presupposed by the former; that the latter is prior in thought to the former; that we conceive accident as something over and above, something superadded to substance as subject. For instance, we can define matter and form without the prior concept of body, or animality and rationality without the prior concept of man; but we cannot define colour without the prior concept of body, or the faculty of speech without the prior concept of man.[251]
Substance, therefore, is prior in thought to accident; but is the substance itself also prior temporally (prior tempore) to its accidents? It is prior in time to some of them, no doubt; the individual human being is thus prior, for instance, to the knowledge he may acquire during life. But there is no reason for saying that a substance must be prior in time to all its accidents;[252] so far as we can discover, no created substance comes into existence devoid of all accidents: corporeal substance devoid of internal quantity, or spiritual substance devoid of intellect and will.
If prior in thought, though not necessarily in time, to its accidents, is a substance prior to its accidents really, ontologically (prior natura)? Yes; it is the real or ontological principle of its accidents; it sustains them, and they depend on it. It is a passive or material cause (using the term “material” in the wide sense, as applicable even to spiritual substances), or a receptive subject, determined in some way by them as formal principles. It is at the same time an efficient and passive cause of some of its own accidents: the soul is an efficient cause of its own immanent processes of thought and volition, and at the same time a passive principle of them, undergoing real change by their occurrence. Of others it is merely a receptive, determinable subject, of those, namely, which have an adequate and necessary foundation in its own essence, and which are called properties in the strict sense: without these it cannot exist, though they do not constitute its essence, or enter into the concept of the latter; but it is not prior to them in time, nor is it the efficient cause of them; it is, however, a real principle of them, an essence from the reality of which they necessarily result, and on which their own reality depends. Such, for instance, is the faculty of thought, or volition, or speech in regard to man.
The accident-mode of being is, therefore, a mode of being which determines a substance in some real way. Its formal effect is to give the substance some real and definite determination: not esse simpliciter but esse tale. With the substance it constitutes a concrete real being which is unum per accidens, not unum per se.
The accident has no formal cause: it is itself a “form” and its causality is that of a formal cause, which consists in its communicating itself to a subject, and, by its union therewith, constituting some new reality—in this case a concrete being endowed with “accidental” unity.
Accidents have of course, a material cause; not, however, in the sense of a materia ex qua, a material from which they are constituted, inasmuch as they are simple “forms”; but in the sense of a subject in which they are received and in which they inhere; and this “material cause” is, proximately or remotely, substance.
Substance also is the final cause, the raison d'être, of the reality of the accidental mode of being. Accidents exist for the [pg 236] perfecting of substances: accidentia sunt propter substantiam. As we have seen already, and as will appear more clearly later on, the fundamental reason for the reality of an accidental mode of being, really distinct from the created or finite substance (for the Infinite Substance has no accidents), is that the created substance is imperfect, limited in its actual perfection, does not exist tota simul, but develops, through a process of change in time, from its first or essential perfection, through intermediate perfections, till it reaches the final perfection ([46]) of its being.
Have all accidents efficient causes? Those which are called common accidents as distinct from proper accidents or properties ([66]) have undoubtedly efficient causes: the various agencies which produce real but accidental changes in the individual substances of the universe. Proper accidents, however, inasmuch as they of necessity exist simultaneously with the substances to which they belong, and flow from these substances by a necessity of the very essence of these latter, cannot be said to have any efficient causes other than those which contribute by their efficiency to the substantial changes by which these substances are brought into actual existence; nor can they be said to be caused efficiently by these substances themselves, but only to “flow” or “result” necessarily from the latter, inasmuch as they come into existence simultaneously with, but dependently on, these substances. Hence, while substances are universally regarded as real principles of their properties—as, for instance, the soul in regard to intellect and will, or corporeal substance in regard to quantity—they are not really efficient causes of their properties, i.e. they do not produce these properties by action. For these properties are antecedent to all action of the substance; nor can a created substance act by its essence, but only through active powers, or faculties, or forces, which meditate between the essence of a created substance and its actions, and which are the proximate principles of these actions, while the substance or nature is their remote principle. Hence the “properties” which necessarily result from a substance or nature, have as their efficient causes the agencies productive of the substance itself.[253]
66. Main Divisions of Accidents.—These considerations will help us to understand the significance of a few important divisions of accidents: into proper and common, inseparable and separable. We shall then be in a position to examine the nature [pg 237] of the distinction between accidents and substance, and to establish the existence of accidents really distinct from substance.