But for heredity he could not lift a finger: he would not have a finger to lift. But for environment he could not learn to use a finger. He could never know good from bad. We all know that we can train and curb ourselves, that we can weed out bad habits, and cultivate good habits. No one has any doubt about that. The question is what causes us to do the one or the other. The answer is--heredity and environment. We can develop our muscles, our brains, our morals; and we can develop them enormously. But before we can do these things we must _want_ to do them, and we must know that we _can_ do them, and how to do them; and all knowledge, and all desire comes from environment and heredity. A youth wishes to be strong. Why? Say he has been reading Mr. Sandow's book. He is told there that by doing certain exercises every day he can very greatly increase his strength. This sets him to work at the dumb-bells. There may be many motives impelling him. One group form a general desire to be strong: that is heredity. But the spur that moves him is Sandow's book, and that spur, and the information as to how to proceed, are environment. The youth begins, and for a few months he does the exercises every morning. But they begin to get irksome. He is tired, he has a slight cold, he wants to read or write. He neglects the exercises. Then he remembers that he cannot get strong unless he perseveres and does the work regularly, and he goes on again. Or he neglects his training for awhile, until he meets another youth who has improved himself. Then he goes back to the dumb-bells. Is not this, to our own knowledge, the kind of thing that happens to us all, in all kinds of self-training, whether it be muscular, mental, or moral? What causes the fluctuations? Let the reader examine his own conduct, and he will find a continual shifting and conflict of motives. And he will never find a motive that cannot be traced to his temperament or training, to his heredity or environment. A man wants to learn French, or shorthand. Let him ask himself why he wants to learn, and he will find the motive springs from temperament or training. He begins to learn. He finds the work difficult and irksome. He has to spur himself on by all kinds of expedients. Finally he learns, or he gives up trying to learn; and he will find that his action has been settled by a contest between his desire to be able to write shorthand, or to speak French, and his dislike to the drudgery of learning; or that his action has been settled by a conflict between his desire to know shorthand, or French, and his desire to do something else. He does the thing he most desires to do. And all desire comes from heredity or from environment. Every member of his body, every faculty, every impulse is fixed for him by heredity; every kind of knowledge, every kind of encouragement or discouragement comes of environment. I hope we have made that quite clear, and now we may ask to what it leads us.