3. Hence that any material substance, which is anywhere by reason of its matter, has within itself a power prepared to act where the substance itself is not present by its matter.
As the actio in distans shocks vulgar prejudices, and has therefore many decided adversaries, it is plain that we must be ready to meet a great number of objections. For the present we respectfully invite those who consider the action at a distance as an obvious impossibility to examine carefully the arguments by which we have established the impossibility of the action by material contact. As to their own reasons for a contrary opinion, we hope to answer them satisfactorily as soon as we have done with the explanation of a few other preliminaries.
Power and velocity.
The question which now presents itself is the following: Is velocity the active power of material substance? This question has some importance in the present state of science, on account of the confusion generally made by physical writers between powers, forces, actions, and movements. We answer that, although active power and velocity are now generally considered as synonymous, they are quite different things. Here are our reasons:
In the first place, it is philosophically [pg 588] evident that the result of an action and the principle of the action cannot be of the same nature. But velocity is certainly the result of an action, whilst the active power is the principle of the action. And therefore velocity and active power cannot be of the same nature. But surely, if velocity has not the nature of an active power, it is not an active power, as every one must admit.
In the second place, the active power of creatures, be they material or immaterial, is the power by the exertion of which they manifest themselves and their natural perfection, thus leading us to the knowledge of the existence and the perfections of our Creator, such a knowledge being the end of creation. Active power is therefore not an accidental and changeable affection, but an essential, primitive, and permanent appurtenance of all created substances; nor does it come from interaction of creatures, but only from creation itself; so that we might well apply to it what S. Paul says of the power of kings and rulers: “There is no power except from God.” And accordingly velocity, which is an accidental and changeable affection of matter, cannot be the active power of the material substance.
In the third place, if velocity were the active principle of matter, matter would have no definite nature of its own. For “nature” is defined as the principle of motion; and material substance would be destitute of such a principle; for velocity, by which it is assumed that it would cause movement, has no part in the constitution of the substance itself. Hence we must conclude that either material substance has no definite nature of its own, or, if this cannot be admitted, the active power of matter is not its velocity.
In the fourth place, a mass of matter at rest acts on the body by which it is supported, and exercises a pressure against it; and therefore matter is active independently of actual movement; which conclusively shows that the active power of matter has nothing common with its velocity.
Lastly, velocity is an accidental mode; and nothing accidental possesses active power, as has been shown in one of our philosophical articles.[136]
Thus it appears that the active power of material substance is not its velocity. Those physicists who acknowledge no other powers but “masses multiplied by velocities” are therefore wholly mistaken. The product of a mass into its velocity does not represent an active power, and not even a dynamical force, but simply the quantity of an effect produced by a previous action. It is true that a mass animated by velocity can do work, which a mass at rest cannot do. But we have shown in the article just mentioned that such a work is done, not by velocity, but by the natural powers inherent in the body, the velocity being only a condition sine qua non. Nor does it matter that the work done by a body is a function of its velocity. This only proves that the greater the velocity of the body, the greater is the resistance required to exhaust it.