But it is possible for one to be less profoundly impressed by the differences which characterize matter and mind. One may feel inclined to refer mental phenomena to matter, and to deny them the prominence accorded them by the dualist. On the other hand, one may be led by one's reflections to resolve material objects into mere ideas, and to claim that they can have no existence except in a mind. Finally, it is possible to hold that both minds and material things, as we know them, are only manifestations, phenomena, and that they must be referred to an ulterior "reality" or "substance." One may claim that they are "aspects" of the one reality, which is neither matter nor mind.

These doctrines are different forms of Monism. In whatever else they differ from one another, they agree in maintaining that the universe does not contain two kinds of things fundamentally different. Out of the duality of things as it seems to be revealed to the plain man they try to make some kind of a unity.

35. MATERIALISM.—The first of the forms of monism above mentioned is Materialism. It is not a doctrine to which the first impulse of the plain man leads him at the present time. Even those who have done no reading in philosophy have inherited many of their ways of looking at things from the thinkers who lived in the ages past, and whose opinions have become the common property of civilized men. For more than two thousand years the world and the mind have been discussed, and it is impossible for any of us to escape from the influence of those discussions and to look at things with the primitive simplicity of the wholly untutored.

But it was not always so. There was a time when men who were not savages, but possessed great intellectual vigor and much cultivation, found it easy and natural to be materialists. This I have spoken of before (section 30), but it will repay us to take up again a little more at length the clearest of the ancient forms of materialism, that of the Atomists, and to see what may be said for and against it.

Democritus of Abdera taught that nothing exists except atoms and empty space. The atoms, he maintained, differ from one another in size, shape, and position. In other respects they are alike. They have always been in motion. Perhaps he conceived of that motion as originally a fall through space, but there seems to be uncertainty upon this point. However, the atoms in motion collide with one another, and these collisions result in mechanical combinations from which spring into being world-systems.

According to this doctrine, nothing comes from nothing, and nothing can become nonexistent. All the changes which have ever taken place in the world are only changes in the position of material particles—they are regroupings of atoms. We cannot directly perceive them to be such, for our senses are too dull to make such fine observations, but our reason tells us that such is the case.

Where, in such a world as this, is there room for mind, and what can we mean by mind? Democritus finds a place for mind by conceiving it to consist of fine, smooth, round atoms, which are the same as the atoms which constitute fire. These are distributed through the whole body, and lie among the other atoms which compose it. They are inhaled with and exhaled into the outer air. While they are in the body their functions are different according as they are located in this organ or in that. In the brain they give rise to thought, in the heart to anger, and in the liver to desire.

I suppose no one would care, at the present time, to become a Democritean. The "Reason," which tells us that the mind consists of fine, round atoms, appears to have nothing but its bare word to offer us. But, apart from this, a peculiar difficulty seems to face us; even supposing there are atoms of fire in the brain, the heart, and the liver, what are the thought, anger, and desire, of which mention is made?

Shall we conceive of these last as atoms, as void space, or as the motion of atoms? There really seems to be no place in the world for them, and these are the mind so far as the mind appears to be revealed—they are mental phenomena. It does not seem that they are to be identified with anything that the Atomistic doctrine admits as existing. They are simply overlooked.

Is the modern materialism more satisfactory? About half a century ago there was in the scientific world something like a revival of materialistic thinking. It did not occur to any one to maintain that the mind consists of fine atoms disseminated through the body, but statements almost as crude were made. It was said, for example, that the brain secretes thought as the liver secretes bile.