Essence of material substance.—We are now ready to answer with all desirable precision and clearness the question, “What is the essence of material substance?”—a question not at all formidable, when the active and the passive principle of matter have been properly defined and elucidated. Our answer is as follows:
The essence, or quiddity, of a thing is really nothing else than its nature; hence if we know the principles which constitute the nature of the material element, we know in fact the essence of material substance. Now, the principles which constitute any given created nature are an act of a certain kind—that is, a certain principle of activity; and a corresponding potency—that is, a corresponding principle of passivity. Whence we conclude that the principles of a material nature are the act by which such a nature is determined to act in a sphere and to cause local movement, and the potency on account of which the same nature is liable to receive local movement. And since the said act is called “the substantial form,” and the said potency “the matter,” we conclude that the essence of material substance consists of matter and substantial form.
This conclusion is by no means new; it expresses, on the contrary, the universal doctrine of the ancient philosophers on the essence of material substance. But it must be observed that we limit this doctrine to the essence of primitive elements, which alone can be rigorously styled “first substances,” whilst the ancients, owing to their imperfect notions of natural things, applied the same doctrine to compound substances, which they believed to arise by substantial generation instead of material composition. Thus our conclusion is more guarded and less comprehensive than that of the old metaphysicians. Moreover, the ancient philosophers, who did not know the primitive elements, but assumed the continuity of matter, could not picture to themselves the intellectual notions of matter and substantial form in a sensible manner, and certainly were unable to find any true sensible image of them; and for this reason their speculations about the essence of material substance remained imperfect and their explanations obscure and unsatisfactory. We, on the contrary, thanks to the investigations and discoveries made in the last centuries, have the advantage of knowing that all matter is subject to gravitation, and acts in a sphere according to a constant and very simple law, which presides over the molecular and chemical no less than the astronomical phenomena; and we are thus enabled to form a true and genuine conception of the matter and form of the primitive element, founded on ascertained facts, and free from false or incongruous imaginations. Hence the words “matter” and “form,” as employed by us, have such a clear and precise sense that no room is left for their misinterpretation.
We therefore know, and clearly too, the essence of primitive material substance, whatever may be said to the contrary by some admirers of the old philosophy, who spurn the discoveries of modern physics, or by some [pg 674] modern thinkers, who revile all metaphysical analysis as mere rubbish.
The essential definition of material substance, as such, is therefore the following: Material substance is a being fit to cause and receive merely local motion. This definition is fuller than the one adopted by the ancients, who defined matter to be “a movable being”—Ens mobile. Of course, when they spoke of a “movable” being, the ancients referred to “local” movement; but, as there are movements of some other kinds, none of which can be produced or received by matter, we prefer to keep the epithet “local” as prominent as possible in our definition, and we add the adverb “merely” as a further limitation required by the nature of the subject. The old definition mentions nothing but the mobility of matter. This is owing to the fact that the ancients had no notion of universal attraction, and considered the activity of material substance as dependent on movement, according to their axiom: Nihil movet nisi motum. But as we know, on the one hand, that the specific differences of things must be derived from their formal rather than from their material constitution, and, on the other, as the constituent form of the material element is an efficient principle of local motion, we include in the definition of matter its aptitude both to produce and to receive local motion “as the complete specific difference” which distinguishes material substance from any other being whatever.
It seems to us that our definition of matter wants neither clearness nor precision. Indeed, we would be unable to make it clearer or more accurate; and as for its soundness, let our readers, who have hitherto followed our reasonings, judge for themselves.
In the opinion of most modern philosophers, the essence of matter consists of extension and resistance. From what has preceded it is evident that this opinion is utterly false. Extension is not a property of matter as such, but only of physical compounds containing a multitude of distinct material points; and, even in this case, it is not the matter, but the volume, or the place circumscribed by the extreme terms of the body, that can be styled “extended,” as we have shown in our last article. As to resistance, it suffices to remark that no accidental act belongs to the essence of substance; hence resistance, which is an accidental act, cannot enter into the definition of matter. Some will say that, if not resistance, at least the power of resisting, belongs to the essence of matter. But not even this is true. The material element has the power of attracting or of repelling; but such a power cannot be considered as formally resisting. Resistance is a particular case of repulsion, when the agent by its repulsive exertion gradually lessens and exhausts the velocity of an approaching mass of matter; but resistance may also be a particular case of attraction, inasmuch as the agent by its attractive exertion gradually lessens and exhausts the velocity of a mass of matter receding from it. Hence all material substance has a motive power, either attractive or repulsive; but neither of them can be described as a resisting power; for attractivity does not resist the movement of an approaching body, nor does repulsivity resist the movement of a receding body. It is scarcely necessary to add that the notion of a resisting power essential to matter is a remnant of the old prejudice consisting in the belief that, when two bodies come in contact, the matter [pg 675] of the one precludes, by its materiality, bulk, and inertia, the further advance of the other. Nothing is more common, with the followers of the ancient theories, than the assumption that the matter of bodies by its quantity and by its occupation of space resists the passage of any other matter. We have shown elsewhere that resistance is action, and therefore is not owing to the inert matter standing in the way of the approaching body, but to the active power of which the inert matter is the centre.
To complete our elucidation of the essential definition of matter, something remains to be said about the inertia of material substance. We shall see that inertia is not a constituent, but only a result of the constitution, of matter; whence it follows that no mention of inertia is needed in the essential definition of material substance. In fact, the notion of this substance includes nothing but the essential act and the essential term, that is, the principle of activity and the principle of passivity, both concerned with local motion only. To have a principle of activity and a principle of passivity is in the nature of all created substances, and constitutes their generic entity; hence the mention of these two principles in our definition serves to point out the genus of material substance; whilst the intrinsic ordination of the same principles to local motion serves to point out the essential difference which separates matter from any other substance.
Inertia.—Many confound the inertia of matter with its passivity, and consider inertia as one of the essential constituents of matter. It is not difficult, however, to show that inertia and passivity are two distinct properties. Those who reduce the principles of real being to an act and a term, without taking notice of its essential complement,[157] reduce in fact the intrinsic properties of real being to activity and passivity, the one proceeding from the act, and the other from the potential term; and thus the inertia of matter, for which they cannot account by any distinct principle, is considered by them as an attribute of matter identical with, or at least involved in, its real passivity. The truth is that, as the act and the potency, which constitute the essence of a material being, are the formal source of its actuality, so also the activity connatural to that act, and the passivity connatural to that potency, are the formal source of the inertia by which the same being is characterized. This will be easily understood by a glance at the nature of inertia.
That inertia is not passivity is clear enough; for passivity is the potentiality of receiving an impression from without, whereas inertia is the incapability of receiving an impression from within; passivity is that on account of which matter receives the determination to move, whereas inertia is that on account of which matter cannot change that determination, but is obliged to obey it, by moving with the received velocity in the given direction. The determination to move is received only while the agent acts, that is, as long as the passivity is being actuated, and no longer; whereas the movement itself, which follows such a determination, continues, owing to inertia, without need of continuing the action, so that, if all further action were to cease, the moving matter, owing to its inertia, would persevere in its movement for ever.