The reader who has closely followed our main idea, which will be further illustrated, will anticipate that the question of matter and force finds its solution in the understanding of the relation between the general and the special. What is the relation of the concrete to the abstract? This is the common problem of those who see the active impulse of the world either in the spiritual force or in the material substance, who think to find the nature of things, the non plus ultra of science, in either of these facts.
Liebig, who is especially fond of straying from his inductive science into the field of speculative thought, says in an idealist sense: "Force cannot be seen, we cannot grasp it with our hands; in order to understand its nature and peculiarities, we must investigate its effects." And if a materialist replies to him: "Matter is force, force is matter, no matter without force, no force without matter," it is plain that either has determined this relation only negatively. In certain shows, the clown is asked by the manager: "Clown, where have you been?" "With the others," answers the clown. "And where were the others?"—"With me."
In this case we have two answers with the same content, in the other we have two camps which quarrel with different words about an indisputable fact. And this dispute is so much more ridiculous because it is taken so seriously. If the idealist makes a distinction between matter and force, he does not mean to deny that the real phenomenon of force is inseparably linked with matter. And if the materialist claims that there is no matter without force and no force without matter, he does not mean to deny that matter and force are different, as his opponent claims.
The dispute exists for a good reason and has its object, but this object is not revealed in the dispute. It is instinctively kept under cover by both parties, so that they may not be in a position where they would have to acknowledge their own ignorance. Each wants to prove to the other that the other's explanations are inadequate, and both demonstrate this sufficiently. Büchner admits in the closing statements of his "Matter and Force" that the empirical material is insufficient to permit of definite answers to transcendental questions, and that therefore no positive answer can be given to them. And he furthermore says that the empirical material "is fully sufficient to answer them negatively and to do away with hypothesis." This is saying in so many words that the science of the materialist is adequate for the proof that his opponent knows nothing.
The spiritualist or idealist believes in a spiritual, which means in a ghostlike and inexplicable, nature of force. The materialist thinkers, on the other hand, are skeptical. A scientific proof of faith or of skepticism does not exist. The materialist has only this advantage over his idealist opponent, that he looks for the transcendental, the nature, the cause, the force, not back of the phenomenon, not outside of matter. But he remains behind the idealist when he ignores the difference between matter and force. The materialist dwells on the actual inseparability of matter and force and does not admit any other reason for a distinction between the two than "an external reason derived from the demand of our mind for systematization." Büchner says in "Nature and Mind," page 66: "Force and matter, separated from one another, are for me nothing but thoughts, fantasies, ideas without any substance, hypotheses which do not exist for any healthy study of nature, because all phenomena of nature are rendered obscure and unintelligible by such a separation." But if Büchner deals with any special department of natural science in a productive way, instead of handling phrases of natural philosophy, his own practice will show him that the separation of forces from matter is not an "external," but an internal, an imminent necessity, by which alone we are enabled to elucidate and understand the phenomena of nature. Although the author of "Force and Matter" chose for his motto: "Now, what I want is—facts," we assure the reader that this device is more a thoughtless word than a serious opinion. Materialism is not so coarse-grained that it wants purely facts. Those facts which Büchner is looking for are by themselves not specifics for his desires. The idealist likewise wants such facts. No student of nature wants mere hypotheses. What all cultivators of the field of science want is not so much facts as explanations or an understanding of facts. Even the materialist will not deny that science, the "natural philosophy" of Büchner not excepted, is more concerned with mental forces than with bodily matter, that it cares more for force than for matter. The separation of force and matter is derived from "the demand of our mind for systematization." Very true! But so does all science emanate from the demand of our reason for systematization.
The contradistinction between force and matter is as old as that between idealism and materialism. The first conciliation between the two was attempted by imagination which, through the belief in spirits, suggested a secret nature as the cause of all natural phenomena. Science has of late expelled many of these special spirits by replacing the fantastic demons with scientific, or general, explanations. And after we have succeeded in explaining the demon of "pure" reason, it is not difficult to expel the special spirit of force by the general explanation of its nature and thus to reconcile scientifically the contradiction between spiritualism and materialism.
In the universe which constitutes the object of science and of the faculty of reason, both force and matter are unseparated. In the world of sense perceptions force is matter and matter is force. "Force cannot be seen." Oh, yes! Seeing itself is pure force. Seeing is as much an effect of its object as an effect of the eye, and this double effect and other effects are forces. We do not see the things themselves, but their effects on our eyes. We see their forces. And force cannot alone be seen, it can also be heard, smelled, tasted, felt. Who will deny that he can feel the force of heat, of cold, of gravitation? We have already quoted the words of Professor Koppe to the effect that we "cannot perceive heat itself, we merely conclude from its effects that this force exists in nature." This is saying in other words that we do not see, hear, or feel the things themselves, but their effects or forces.
It is just as true to say that we feel matter and not its force as it is to say that we feel force and not matter. Indeed, both are inseparable from the object, as we have already remarked. But by means of the faculty of thought we separate from the simultaneously and successively occurring phenomena the general and the concrete. For instance, we abstract the general concept of sight from the various phenomena of our sight and distinguish it by the name of power of vision from the concrete objects, or substances, of our eyes. From a multitude of sense perceptions we develop by means of reason the general element. The general element of different water phenomena, for instance, is the water power distinguished from the substance of the water. If levers of different materials but of the same length have the same power, it is plain that in this case force is different from matter only in so far as it represents the general element of various substances. A horse does not pull without force, and this force does not pull without the horse. Indeed, in practice the horse is force and force is the horse. But nevertheless we may distinguish the power of pulling from other qualities of the horse, or we may refer to the common element in different services of horses as general horse power, without thereby starting from any other hypothesis than we do in distinguishing the sun from the earth. For in reality the sun does not exist without the earth, nor the earth without the sun.
The world of sense perceptions is made known to us only by our consciousness, but consciousness is conditioned on the world of sense perceptions. Nature is infinitely united or infinitely separated, according to whether we regard it from the standpoint of consciousness as an unconditional unit or from the standpoint of sense perceptions as an unconditional multiplicity. There is truth in both unity and multiplicity, but it is truth only relatively speaking, under certain conditions. It matters a great deal whether we look about with the eyes of the body or with the eyes of the mind. For the eyes of the mind, matter is force. For the eyes of the body, force is matter. The abstract matter is force, the concrete force is matter. Matter is represented by the objects of the hand, of practice, while force is an object of understanding, of science.