=The Phenomena of Dissociation.= When an idea or a complex, a perception or a memory is either temporarily or permanently shoved out of consciousness into the subconscious, it is said to be dissociated.  When we are asleep, the part of us that is usually conscious is dissociated and the submerged part takes the stage.  When we forget our surroundings in concentration or absent-mindedness, a part of us is dissociated and our friends say that we are “not all there,” or as popular slang has it, “Nobody home.”  When a mood or system of complexes drives out all other moods, one becomes “a different person.”  But if this normal dissociation is carried a step farther, we may lose the power to put ourselves together again, and then we may truly be said to be dissociated.  Almost any part of us is subject to this kind of apparent loss.  In neurasthenia the happy, healthy complexes which have hitherto dominated our lives may be split off and left lying dormant in the subconscious; or the power of will or concentration may seem to be gone.  In hysteria we may seem to lose the ability to see or feel or walk, or we may lose for the time all recollection of certain past events, or of whole periods of our lives, or of everything but one system of ideas which monopolizes the field of attention.  Sometimes great systems of memories, instincts, and complexes are alternately shifted in and out of gear, leaving first one kind of person on top and then another.[25] Stevenson’s Dr. Jekyll and Mr. Hyde is not so fantastic a character as he seems.  Any one who doubts the ability of the mind to split itself up into two or more distinct personalities, entertaining totally different conceptions of life, disliking each other, playing tricks on each other, writing notes to each other, and carrying on a perpetual feud as each tries to get the upper hand, should read Morton Prince’s “Dissociation of a Personality,” a fascinating account of his famous case, Miss Beauchamp.

[Footnote 25:  When a memory or system of memories is suddenly lost from consciousness the person is said to be suffering from amnesia or pathological loss of memory.]

=Internal Warfare.= Conflict, often accentuated by shock or fatigue, represses or drives down certain ideas, perceptions, wishes, memories, or complexes into the subconscious, where they remain, sometimes dormant and passive but often dynamic, emotional, carrying on an over-excited, automatic activity, freed from the control of reason and the modifying influence of other ideas, and able to cause almost any kind of disturbance.  So long as there is team-work between the various parts of our personality we are able to act as a unit; but just as soon as we break up into factions with no communication between the warring camps, so soon do we become quite incapable of cooerdination or adjustment, like a nation torn by civil war.  Many of the seemingly fantastic and bizarre mental phenomena of which a human being is capable are the result of this kind of disintegration.