Disputationes metaphysicae

1. Some contend that an accident is to be called only an instrumental principle. And this opinion is commonly attributed to St. Thomas, who intimates it In I, dist. 3, q. 4, a. 3, ad 2; and therefore his followers more frequently follow it, and confirm it with these reasons. First, because the accident is essentially subordinated to the substance in being, and consequently also in action. Secondly, because the accident receives its whole power of acting from the substance. Nor does it stand in the way that the proximate principal cause also receives its power of acting from the first; for the second and the first cause are of diverse orders, and it is not repugnant that an inferior principal cause should receive power from a cause of a superior order; but the accident in acting is of the same order as its substance, and with it constitutes one integral proximate agent, and receives its power of acting from it; but to receive power in this way from another of the same order, constituting with it one proximate agent, is proper to an instrumental cause. Thirdly, because such as being is, such is acting; but the being of the accident belongs to the substance, for an accident is a being of a being; therefore the acting of the accident principally belongs to the substance; therefore it belongs to the accident only instrumentally. And the way of speaking of all philosophers confirms this, who attribute all these actions to substances as to first agents.

2. The contrary opinion is held more frequently by other Doctors, as may be seen in Scotus, In IV, dist. 13, q. 3; Paludanus, q. 4, concl. 1; Major, q. 1; Giles, Quodl. III, q. 1, and theor. 43. To declare the foundation of this opinion, however, it must be supposed that there is no question here of the principal cause ut quod, or that which operates, but of the principal principle quo. For it is established that in the former way it is the supposit that operates; but if it is taken formally, as it is the per se cause of accidental action, it must be taken as it underlies the accidental form which is the principle of such action; for thus Aristotle said that Polyclitus makes the statue per accidens, but the artificer per se. In this way, then, the accident is called the principal cause as principle quo, but the supposit, as underlying the accident, as principle quod. And so this opinion is proved: because the accidental form effects another accident by its own power; but the principal cause is that which operates by its own power; therefore. The major is evident when heat effects heat, and universally one accident another like it, or when a nobler accident effects a less noble one, as light heat; for then the perfection of the effect does not exceed the perfection of the accident which is the principle of acting; therefore neither does it exceed its power; therefore then the accident by its own power is the principle of such action. According to which reason this opinion is to be understood of the accident when it operates in this way; for if a lower accident is elevated to effect another of a higher notion, it will not be denied to be an instrument. Let the second reason be that that is the principal principle of acting to which the effect is likened; but through heating as such the effect becomes like the cause in heat; therefore heat is the principal principle of that action. The third, because heat separated per se from the substance exercises its action with the same force and efficacy, so that it needs neither the influx of the substance nor of another cause supplying it, as all confess of the accidents of the Eucharist as regards accidental actions. The fourth, because whiteness, for example, does not effect intentional species as an instrument of the substance, since to that action the substance seems to be related wholly per accidens.

3. This controversy, supposing what has been said in the second doubt, seems able to be only about the way of speaking; for as regards the thing it concerns only what influx the accident requires from the substance in order to accomplish its proper action. But this being established and declared, there can be controversy only about the signification of a name, when it is asked whether it is to be called an instrument or a principal principle. Thus the powers of the soul, for vital actions, can deservedly be called instruments conjoined to the soul, inasmuch as they are subordinated to it as to the principal form, so that they cannot effect their operations without its actual influx and as it were motion; although on another ground they can be called principal principles, at least partial ones, namely, because the power which they have in themselves, and by which they cooperate to the effect, is of itself proportioned and commensurate to such an effect, because it does not exceed the perfection of the faculty itself; for I speak of connatural actions. Hence too the power and the form can be compared as the universal and the proximate principle, but each principal and sufficient and total in its order; yet, because between those two the form is more principal, to which the power is subordinated, this subordination and dependence can be signified by the name of instrument.

4. But in other accidents, which do not so depend in their action on the substantial form, much less of the notion of instrument is found with respect to such actions. Hence, as regards the thing, they are most truly reckoned principal principles of such actions, as the arguments made in the latter place convince, because by virtue of that perfection alone which they have from their species or entity they elicit such actions. Likewise, because such a form alone suffices per se to give the supposit the being per se and formally required for such an action; as in hot water the being per se required for heating is only being hot. Just as, then, heat is a form per se and from its proper notion giving being hot, so in reality it is the principal principle of heating. Nor does it matter or stand in the way that the accident is in the substance and for the sake of the substance and from the substance, because we are not treating of whence, or from what causes, the accident has the power of acting; for we confess that it has it materially from the substance and finally for its sake, and perhaps also efficiently, mediately or immediately, through natural emanation; but we are treating of whether formally it has in itself the whole power sufficient and necessary for that action. And thus we say it has it, and this alone we contend is signified when it is called the principal cause, not ut quod, but ut quo. To which principle it stands in no way opposed that the accident is a being of a being, that is, of the substance, and that its whole being belongs to another; rather that particle ut quo seems to hint and signify all these things. Hence even the substantial form itself, inasmuch as it is the principle quo with respect to its supposit, is in its own way a being of a being. Lest, however, there be contention about a name, we shall also grant this to the former opinion: that if by the name of instrument or instrumental cause there is signified only (as indeed it sometimes is signified) that relation which the accident has to the substance, inasmuch as it was given in order that the substance might operate through it as through its instrument, and for this receives its power from the substance itself and is sustained by and depends on the same in its being, then in this way it can be called an instrument; yet it is more properly called the power or potency of the substance.