If I could, I would begin this book by telling you what Life is. But unfortunately I do not know what Life is. The only consolation I can find is in the fact that nobody else knows either.

We ask the churches, and they tell us that male and female created He them, and put them in the Garden of Eden, and they would have been happy had not Satan tempted them. But then you ask, who made Satan, and the explanation grows vague. You ask, if God made Satan, and knew what Satan was going to do, is it not the same as if God did it himself? So this explanation of the origin of evil gets you no further than the Hindoo picture of the world resting on the back of a tortoise, and the tortoise on the head of a snake—and nothing said as to what the snake rests on.

Let us go to the scientist. I know a certain physiologist, perhaps the greatest in the world, and his eager face rises before me, and I hear his quick, impetuous voice declaring that he knows what Life is; he has told it in several big volumes, and all I have to do is to read them. Life is a tropism, caused by the presence of certain combinations of chemicals; my friend knows this, because he has produced the thing in his test-tubes. He is an exponent of a way of thought called Monism, which finds the ultimate source of being in forms of energy manifesting themselves as matter; he shows how all living things arise from that and sink back into it.

But question this scientist more closely. What is this "matter" that you are so sure of? How do you know it? Obviously, through sensations. You never know matter itself, you only know its effects upon you, and you assume that the matter must be there to cause the sensation. In other words, "matter," which seems so real, turns out to be merely "a permanent possibility of sensation." And suppose there were to be sensations, caused, for example, by a sportive demon who liked to make fun of eminent physiologists—then there might be the appearance of matter and nothing else; in other words, there might be mind, and various states of mind. So we discover that the materialist, in the philosophic sense, is making just as large an act of faith, is pronouncing just as bold a dogma as any priest of any religion.

This is an old-time topic of disputation. Before Mother Eddy there was Bishop Berkeley, and before Berkeley, there was Plato, and they and the materialists disputed until their hearers cried in despair, "What is Mind? No matter! What is Matter? Never mind!" But a century or two ago in a town of Prussia there lived a little, dried-up professor of philosophy, who sat himself down in his room and fixed his eyes on a church steeple outside the window, and for years on end devoted himself to examining the tools of thought with which the human mind is provided, and deciding just what work and how much of it they are fitted to do. So came the proof that our minds are incapable of reaching to or dealing with any ultimate reality whatever, but can comprehend only phenomena—that is to say, appearances—and their relations one with another. The Koenigsberg professor proved this once for all time, setting forth four propositions about ultimate reality, and proving them by exact and irrefutable logic, and then proving by equally exact and irrefutable logic their precise opposites and contraries. Anybody who has read and comprehended the four "antinomies" of Immanuel Kant[A] knows that metaphysics is as dead a subject as astrology, and that all the complicated theories which the philosophers from Heraclitus to Arthur Balfour have spun like spiders out of their inner consciousness, have no more relation to reality than the intricacies of the game of chess.

The writer is sorry to make this statement, because he spent a lot of time reading these philosophers and acquainting himself with their subtle theories. He learned a whole language of long words, and even the special meanings which each philosopher or school of philosophers give to them. When he had got through, he had learned, so far as metaphysics is concerned, absolutely nothing, and had merely the job of clearing out of his mind great masses of verbal cobwebs. It was not even good intellectual training; the metaphysical method of thought is a trap. The person who thinks in absolutes and ultimates is led to believe that he has come to conclusions about reality, when as a matter of fact he has merely proved what he wants to believe; if he had wanted to believe the opposite, he could have proven that exactly as well—as his opponents will at once demonstrate.

If you multiply two feet by two feet, the result represents a plain surface, or figure of two dimensions. If you multiply two feet by two feet by two feet, you have a solid, or figure of three dimensions—such as the world in which we live and move. But now, suppose you multiply two feet by two feet by two feet by two feet, what does that represent? For ages the minds of mathematicians and philosophers have been tempted by this fascinating problem of the "fourth dimension." They have worked out by analogy what such a world would be like. If you went into this "fourth dimension," you could turn yourself inside out, and come back to our present world in that condition, and no one of your three-dimension friends would be able to imagine how you had managed it, or to put you back again the way you belonged. And in this, it seems to me, we have the perfect analogy of metaphysical thinking. It is the "fourth dimension" of the mind, and plays as much havoc with sound thinking as a physical "fourth dimension" would play with—say, the prison system. A man who takes up an absolute—God, immortality, the origin of being, a first cause, free will, absolute right or wrong, infinite time or space, final truth, original substance, the "thing in itself"—that man disappears into a fourth dimension, and turns himself inside out or upside down or hindside foremost, and comes back and exhibits himself in triumph; then, when he is ready, he effects another disappearance, and another change, and is back on earth an ordinary human being.

The world is full of schools of thought, theologians and metaphysicians and professors of academic philosophy, transcendentalists and theosophists and Christian Scientists, who perform such mental monkey-shines continuously before our eyes. They prove what they please, and the fact that no two of them prove the same thing makes clear to us in the end that none of them has proved anything. The Christian Scientist asserts that there is no such thing as matter, but that pain is merely a delusion of mortal mind; he continues serene in this faith until he runs into an automobile and sustains a compound fracture of the femur—whereupon he does exactly what any of the rest of us do, goes to a competent surgeon and has the bone set. On the other hand, some devoted young Socialists of my acquaintance have read Haeckel and Dietzgen, and adopted the dogma that matter is the first cause, and that all things have grown out of it and return to it; they have seen that the brain decays after death, they declare that the soul is a function of the brain—and because of such theories they deliberately reject the most powerful modes of appeal whereby men can be swayed to faith in human solidarity.

The best books I know for the sweeping out of metaphysical cobwebs are "The Philosophy of Common Sense" and "The Creed of a Layman," by Frederic Harrison, leader of the English Positivists, a school of thought established by Auguste Comte. But even as I recommend these books, I recall the dissatisfaction with which I left them; for it appears that the Positivists have their dogmas like all the rest. Mr. Harrison is not content to say that mankind has not the mental tools for dealing with ultimate realities; he must needs prove that mankind never will and never can have these tools, I look back upon the long process of evolution and ask myself, What would an oyster think about Positivism? What would be the opinion of, let us say, a young turnip on the subject of Mr. Frederic Harrison's thesis? It may well be that the difference between a turnip and Mr. Harrison is not so great as will be the difference between Mr. Harrison and that super-race which some day takes possession of the earth and of all the universe. It does not seem to me good science or good sense to dogmatize about what this race will know, or what will be its tools of thought. What does seem to me good science and good sense is to take the tools which we now possess and use them to their utmost capacity.

What is it that we know about life? We know a seemingly endless stream of sensations which manifest themselves in certain ways, and seem to inhere in what we call things and beings. We observe incessant change in all these phenomena, and we examine these changes and discover their ways. The ways seem to be invariable; so completely so that for practical purposes we assume them to be invariable, and base all our calculations and actions upon this assumption. Manifestly, we could not live otherwise, and the spread of scientific knowledge is the further tracing out of such "laws"—that is to say, the ways of behaving of existence—and the extending of our belief in their invariability to wider and wider fields.

Once upon a time we were told that "the wind bloweth where it listeth." But now we are quite certain that there are causes for the blowing of the wind, and when our researches have been carried far enough, we shall be able to account for and to predict every smallest breath of air. Once we were told that dreams came from a supernatural world; but now we are beginning to analyze dreams, and to explain what they come from and what they mean. Perhaps we still find human nature a bewildering and unaccountable thing; but some day we shall know enough of man's body and his mind, his past and his present, to be able to explain human nature and to produce it at will, precisely as today we produce certain reactions in our test-tubes, and do it so invariably that the most cautious financier will invest tens of millions of dollars in a process, and never once reflect that he is putting too much trust in the permanence of nature.

In many departments of thought great specialists are now working, experimenting and observing by the methods of science. If in the course of this book we speak of "certainty," we mean, of course, not the "absolute" certainty of any metaphysical dogma, but the practical certainty of everyday common sense; the certainty we feel that eating food will satisfy our hunger, and that tomorrow, as today, two and two will continue to make four.