Consciousness only arises late in the course of evolution and
only in connection with adjustments that are relatively complex.
When the same or similar conditions in the environment are
repeatedly presented to the organism so that it is called upon to
react in a similar and almost
identical way each time, there tends to be organized a mechanism
of reaction which becomes more and more automatic and is
accompanied by a state of mind of less and less awareness.[17]

[Footnote 17: White: _Mechanisms of Character Formation_.]

It is easy to see the economy of this arrangement which provides
ready-made patterns of reaction for habitual situations and leaves
consciousness free for new decisions. Since an automatic action,
traveling along well-worn brain paths, consumes little energy and
causes the minimum of fatigue, the plan not only frees consciousness
from a confusing number of details, but also works for the
conservation of energy. While consciousness is busy lighting up the
special problems of the moment, the vast mass of life's demands are
taken care of by the subconscious, which constitutes the bulk of the
mind. "Properly speaking, the unconscious is the real psyche."[18]

[Footnote 18: Freud: _Interpretation of Dreams_, p. 486.]

=The Heart of Psychology.= In the face of all this, it is not to be
wondered at that the problem of the subconscious has been called not
one problem of psychology but the problem. It cannot be denied that
the discoveries which have already been made as to its activities have
been of immense practical importance in the understanding of normal