But we usually find it so hard to revise our theories about ourselves and each other. We hold them as prejudices and not as hypotheses, and when the facts of life seem to disprove them, we either angrily clutch at our theories and snarl in defiance, or we pull them out of us with such a wrench that they draw blood. The scientist’s way is to start with a hypothesis and then to proceed to verify it by experiment. Similarly ought we to approach life and test all our hypotheses by experience. Our methods have been too rigid. We have started with moral dogmas, and when life obstinately refused to ratify them, we have railed at it, questioned its sincerity, instead of adopting some new hypothesis, which more nearly fitted our experience, and testing it until we hit on the principle which explained our workings to ourselves. The common-sense, rule-of-thumb morality which has come down to us is no more valid than the common-sense, scientific observation that the sun goes round the earth. We can rely no longer on the loose gleanings of homely proverb and common sense for our knowledge of personality and human nature and life. If we do not adopt the experimental life, we are still in bondage to convention. To learn of life from others’ words is like learning to build a steam-engine from books in the class-room. We may learn of principles in the spiritual life that have proven true for millions of men, but even these we must test to see if they hold true for our individual world. We can never attain any self-reliant morality if we allow ourselves to be hypnotized by fixed ideas of what is good or bad. No matter how good our principles, our devotion to morality will be mere lip-service unless each belief is individually tested, and its power to work vitally in our lives demonstrated. But this moral experimentation is not the mere mechanical repetition of the elementary student in the laboratory, who makes simple experiments which are sure to come out as the law predicts. The laws of personality and life are far more complex, and each experiment discovers something really novel and unique. The spiritual world is ever-creative; the same experiments may turn out differently for different experimenters, and yet they may both be right. In the spiritual experimental life, we must have the attitude of the scientist, but we are able to surpass him in daring and boldness. We can be certain of a physical law that as it has worked in the past, so it will work in the future. But of a spiritual law we have no such guarantee. This it is that gives the zest of perpetual adventure to the moral life. Human nature is an exhaustless field for investigation and experiment. It is inexhaustible in its richness and variety.