The primary fact that we know about life is growth. Herbert Spencer has defined this growth, or evolution, in a string of long words which may be summed up to mean: the process whereby a number of things which are simple and like one another become different parts of one thing which is complex. If we observe this process in ourselves, and the symptoms of it in others, we discover that when it is proceeding successfully, it is accompanied by a sensation of satisfaction which we call happiness or pleasure; also that when it is thwarted or repressed, it is accompanied by a different sensation which we call pain. Subtle metaphysicians, both inside the churches and out, have set themselves to the task of proving that there must be some other object of life than the continuance of these sensations of pleasure which accompany successful growth. They have proven to their own satisfaction that morality will collapse and human progress come to an end unless we can find some other motive, something more permanent and more stimulating, something "higher," as they phrase it. All I can say is that I gave reverent attention to the arguments of these moralists and theologians, and that for many years I believed their doctrines; but I believe them no longer.

I interpret the purpose of life to be the continuous unfoldment of its powers, its growth into higher forms—that is to say, forms more complex and subtly contrived, capable of more intense and enduring kinds of that satisfaction which is nature's warrant of life. If you wish to take up this statement and argue about it, please wait until you have read the chapter "Nature and Man," and noted my distinction between instinctive life and rational life. For men, the word "growth" does not mean any growth, all growth, blind and indiscriminate growth. It does not mean growth for the tubercle bacillus, nor growth for the anopheles mosquito, nor growth for the house-fly, the spider and the louse. Neither do we mean that the purpose of man's own life is any pleasure, all pleasure, blind and indiscriminate pleasure; the pleasure of alcohol, the pleasure of cannibalism, the pleasure of the modern form of cannibalism which we call "making money." We have survived in the struggle for existence by the cooperative and social use of our powers of judgment; and our judgment is that which selects among forms of growth, which gives preference to wheat and corn over weeds, and to self-control and honesty over treachery and greed.

So when we say that the purpose of life is happiness, we do not mean to turn mankind loose at a hog-trough; we mean that our duty as thinkers is to watch life, to test it, to pick and choose among the many forms it offers, and to say: This kind of growth is more permanent and full of promise, it is more fertile, more deeply satisfactory; therefore, we choose this, and sanction the kind of pleasure which it brings. Other kinds we decide are temporary and delusive; therefore we put in jail anyone who sells alcoholic drink, and we refuse to invite to our home people who are lewd, and some day we shall not permit our children to attend moving picture shows in which the modern form of cannibalism is glorified.

The reader, no doubt, has been taught a distinction between "science" and "faith." He is saying now, "You believe that everything is to be determined by human reason? You reject all faith?" I answer, No; I am not rejecting faith; I am merely refusing to apply it to objects with which it has nothing to do. You do not take it as a matter of faith that a package of sugar weighs a pound; you put it on the scales and find out—in other words, you make it a matter of experiment. But all the creeds of all the religious sects are full of pronouncements which are no more matters of faith than the question of the weighing of sugar. Is pork a wholesome article of food or is it not? All Christians will readily acknowledge that this is a matter to be determined by the microscope and other devices of experimental science; but then some Jew rises in the meeting and puts the question: Is dancing injurious to the character? And immediately all members of the Methodist Episcopal Church vote to close the discussion.

What is faith? Faith is the instinct which underlies all being, assuring us that life is worth while and honest, a thing to be trusted; in other words, it is the certainty that successful growth always is and always will be accompanied by pleasure. The most skeptical scientist in the world, even my friend the physiologist who proves that life is nothing but a tropism, and can be produced by mixing chemicals in test-tubes—this eager friend is one of the most faithful men I know. He is burning up with the faith that knowledge is worth possessing, and also that it is possible of attainment. With what boundless scorn would he receive any suggestion to the contrary—for example, the idea that life might be a series of sensations which some sportive demon is producing for the torment of man! More than that, this friend is burning up with the certainty that knowledge can be spread, that his fellow men will receive it and apply it, and that it will make them happy when they do. Why else does he write his learned books in defense of the materialist philosophy?

And that same faith which animates the great monist animates likewise every child who toddles off to school, and every chicken which emerges from an egg, and every blade of grass which thrusts its head above the ground. Not every chicken survives, of course, and all the blades of grass wither in the fall; nevertheless, the seeds of grass are spread, and chickens make food for philosophers, and the great process of life continues to manifest its faith. In the end the life process produces man, who, as we shall presently see, takes it up, and judges it, and makes it over to suit himself.

You will note from this that I am what is called an optimist; whereas some of the great philosophers of the world have called themselves pessimists. But I notice with a smile that these are often the men who work hardest of all to spread their ideas, and thus testify to the worthwhileness of truth and the perfectibility of mankind. There has come to be a saying among settlement workers and physicians, who are familiar with poverty and its effects upon life, that there are no bad babies and good babies, there are only sick babies and well babies. In the same way, I would say there are no pessimists and optimists, there are only mentally sick people and mentally well people. Everywhere throughout life, both animal and vegetable, health means happiness, and gives abundant evidence of that fact. All healthy life is satisfactory to itself; when it develops reason, it tries to find out why, and this is yet another testimony to the fact that having power and using it is pleasant. When I was in college the professor would propound the old question: "Would you rather be a happy pig or an unhappy philosopher?" My answer always was: "I would rather be a happy philosopher." The professor replied: "Perhaps that is not possible." But I said: "I will prove that it is!"