We all know that men often do things which they know to be wrong. When we halt between the desire to do a thing, and the feeling that we ought not to do it, we seem to have two minds within us, and these two minds dispute about the decision.
What is this "mysterious" double-self? It is nothing but the contest between heredity and environment; and is not mysterious at all.
Heredity is very old. It reaches back, to the beasts. It passes on to us, generation after generation, for millions of years, certain instincts, impulses, or desires of the beast.
Environment is new. It begins at the cradle. It prints upon us certain lessons of right and wrong. It tells us that we ought not to do certain things.
But the desire to do those things is part of our heredity. It is in our blood. It is persistent, turbulent, powerful. It rises up suddenly, with a glare and a snarl, like a wild beast in its lair. And at the sound of its roar, and the flame of its lambent eyes, and the feel of its fiery breath, memory lifts its voice and hand, and repeats the well-learned lesson with its "shall-nots."
We are told that the animal impulses dwell in the "hind brain," and that morals and thought dwell in the "fore brain." The "dual personality," then, the "double-self," consists of the two halves of the brain; and the dispute between passion and reason, or between desire and morality, is a conflict between the lower man and the higher; between the old Adam and the new.
But it is also, to a great extent, a conflict between the average man and the hero, or leader.
We inherit the roots of morality, that is ta say, the "social instincts," or impulses of unselfish thoughts for others, from the sociable animals. But what we call "ethics," the rules or laws of moral conduct, have been slowly built up by human teachers. These teachers have been men with a special genius for morals. They have made codes of morals higher than the nature of the average man can reach.
But the average man has been taught these codes of morals in his childhood, and has grown up in unquestioning respect for them.
So when his baser nature prompts him to an act, and his memory repeats the moral lesson it has learnt, we have the nature of the average man confronted by the teaching of the superior or more highly moral man.