from the habits and necessities of practical life;—images of this kind throw no light on the inner nature of things.
Moreover, if there is a truth that science has placed beyond dispute, it is that of the reciprocal action of all parts of matter upon each other. Between the supposed molecules of bodies the forces of attraction and repulsion are at work. The influence of gravitation extends throughout interplanetary space. Something, then, exists between the atoms. It will be said that this something is no longer matter, but force. And we shall be asked to picture to ourselves, stretched between the atoms, threads which will be made more and more tenuous, until they are invisible and even, we are told, immaterial. But what purpose can this crude image serve? The preservation of life no doubt requires that we should distinguish, in our daily experience, between passive things and actions effected by these things in space. As it is useful to us to fix the seat of the thing at the precise point where we might touch it, its palpable outlines become for us its real limit, and we then see in its action a something, I know not what, which, being altogether different, can part company with it. But since a theory of matter is an attempt to find the reality hidden beneath these customary images which are entirely relative to our needs, from these images it must first of all set itself free. And, indeed, we see force and matter drawing nearer together the
