Parts of experience or of inherited tendencies may fail to become organically connected with the main parts of our minds, simply because attention has never been focussed on them, or has not attempted to bring them into relation with the rest. They are, shall we say, like bricks which might have been used in a building, but have been left lying on the ground by the workmen.
Still more remarkable are the methods by which harmony is achieved in the personal mind. It is obvious that a conflict of any sort between parts of the mind will waste energy, will prevent a clear-cut reaction being given in either direction, and so constitute a grave biological disadvantage by making us fall between two stools. If a child gets a serious fright in the dark, darkness will tend to arouse fear. But darkness also comes with evening and with the time for sleep. Two modes of reaction to darkness are therefore given, and they are self-contradictory. One part of the mind comes down its pathway towards action, and finds itself met by another which is coming along the same path in the opposite direction. If neither moves, there is a conflict; in our hypothetical case sleep is delayed; and if it comes, is disturbed by nightmares--the echoes of the fright--and the childish organism suffers.
Exactly similar conflicts in which fear plays a part may occur in adult life, e.g., in so-called “shell-shock”; or the sex-instinct may come into conflict with other parts of the personality.
These conflicts are resolved through one tendency or part of experience being passed into the subconscious, where it no longer can meet its opponent on the path to action. And this passage into the subconscious can be apparently automatic, unwitting, when it is called _suppression_, or performed only by voluntary effort, when it is called _repression_. In the former case, it would appear that the conflict may wholly or almost wholly cease; whereas in the second, the repressed portion of mind is perpetually striving to come to the surface again, and must thus perpetually be held down by force.
If we hold by our metaphor of the building, then in suppression, bricks which would not go well with the rest are stacked quietly in the cellars; while in repression, part of the workmen want to build a different sort of building, and have to be forcibly held down by some of the rest to prevent their doing so.