Which will win appears to depend primarily upon the kind of endocrines that predominate in the make-up of the individual, secondarily with his education.  For it is the endocrines that are really in conflict when there is a struggle between two instincts.  And if one endocrine system conquers, it must be either because it is inherently stronger, its secretion potential, that is, the amount of secretion it can put forth as a maximum, is greater (so explaining the term dominant)—­or because a past experience has conditioned it to respond, although the opposing endocrine system does not.  Fear and anger, respectively bound up with the activities of the adrenal medulla and cortex, we shall see, provide as good exemplars as any of this process.

The response of the ductless glands to situations varies with their congenital capacity, and acquired susceptibility.  Capacity is a question of internal chemistry, modifiable by injury, disease, accident, shock, exhaustion.  Susceptibility depends upon the play of the forces focusing upon them that may be summed up as associations.  In the ability of one endocrine system to inhibit another we have the germ of the unconscious.  Hence the modus operandi of the repressions and suppressions, compensations and dissociations, which may unite to integrate or refuse to integrate, and so disintegrate and deteriorate a personality.

As the personality develops, the vegetative system becomes susceptible to the manifold associates of family, school, church and society, art, science and religion, and last but not least sex.  All the different nuances of personality are expressions of a particular relationship, transitory or permanent, between the endocrines and the viscera and muscles.  Conversely, behaviour shows what a person actually is chemically; that is, what endocrine and vegetative factors predominate in his make-up.

FEAR, ANGER, AND COURAGE

Fear and anger are the oldest and so the most deep-rooted of the instincts.  An ameba, contracting at the touch of some unpleasant object, feels fear in its most primitive form.  And anger, the destructive passion, must have appeared early upon the scene of life.  Certainly these two instincts were definitely developed and fixed in the cells before sex differentiation and the sex instincts were born at all.  It is interesting to note this for our rabid Freudians.

Fear and anger involve the adrenal gland.  How comes it that two states of mind so contrasted should involve the same area?  The answer lies in the bipartite construction of the adrenal.  All the evidence points to its medulla as the secretor of the substance which makes for the phenomena of fear, and to its cortex as dominant in the reactions of anger.