Man is a machine. All his deeds, actions, words, thoughts, feelings, convictions, opinions, and habits are the results of external influences, external impressions. Out of himself a man cannot produce a single thought, a single action. Everything he says, does, thinks, feels — all this happens . . . But it is one thing to understand with the mind and another thing to feel it with one’s ‘whole mass,’ to be really convinced that it is so and never forget it.