Dissociation is pathological forgetting. Emotion is the life of an idea. In ordinary forgetting a memory sinks into the subconscious because insufficient interest is attached to it to enable it to remain in consciousness; if, however, an idea associated with some strong emotion is repressed into the subconscious, that emotion will, as it were, vivify it, and cause it to have an independent life of its own; it splits off from the personality and is said to be dissociated. It will be noted that in our study of memory we saw that ideas never remain solitary, but tend to form associations among themselves, or, as they are technically termed, complexes. The dissociated idea is no exception to this rule; not only does it form alliances with its fellow prisoners, but its chains of associations manage to evade the censor and ramify through the other levels of the mind with far-reaching consequences, giving rise to much of the illogicality and unreasonableness which disturb our attempts at rational thinking. We have already noted that a complex is a group of ideas held together by some emotionally toned interest; and as all emotion has its root in an instinct, it follows that all complexes must be affiliated to one or other of the instincts; as they sink into the subconscious they therefore go down the channel of the instinct to which they belong, and as they are swimming against the current they tend to block the flow of that particular instinct and to cause it to express itself through the subsidiary channel which they are endeavouring to open up. It can readily be seen that serious consequences must arise from an obstacle lodged in the fairway of so great a force and drawing to itself, under the law of association of ideas, all thoughts that may enter the mind on the same subject, or that have a real or symbolic resemblance to it. As has been truly said, the subconscious grows at the expense of the conscious, and the balance of the mind is upset; the thrust of life, the source of all energy, instead of flowing freely from level to level, is blocked by the complex and held up in the subconscious, causing the pressure on that level to rise to danger-point, while the conscious mind is sapped of its vitality, producing an individual of imperative and chaotic needs, which he is unable to formulate, even to himself, and with no power to give them expression or obtain their satisfaction. CHAPTER XVIII SYMBOLISATION We may picture the dissociated complex, with the pressure of an instinct behind it, constantly seeking to evade the censor and return to consciousness, where its wishes can be translated into action; and see how the censor, reinforced by the whole weight of the character, resolutely refuses to permit its escape.