We have in hunger the wish reduced to the lowest terms, the most primitive form of it.  Yet we may resolve all wishes, even the most idealistic, into the same terms.  As the vegetative system becomes habituated by repeated experience to react in the same way to the same stimulus, permutations and combinations of wishes become possible until at length the inscrutable complexities of the behaviour of civilized man are evolved.  We have to thank Von Bechterew, the greatest of Russian physiologists, for these fundamental principles, so important for the understanding of the control of human life and conduct.

The associated reflex, aboriginal ancestor of the involved train of associations that constitute the highest thought, conduct and character, is the unit of the system.  Recall the classic example cited.  If a piece of meat is shown to a dog, his mouth waters.  If now you proceed to ring a bell before offering the meat, his mouth will water only when he sees or smells the meat.  If, however, the ringing of the bell precedes the meat a sufficient number of reactions, a time comes when merely the sound of the bell will cause salivation, without the presence of the meat.  So it is with the associated reactions of the internal secretions.  A stimulus originally indifferent to the endocrines may, by association, the laws of which are many, come to act like a spark to the endocrine-instinct mechanism.  Hence we can account for the subtle play of instinct throughout all thinking.

Even objects resembling the specific excitant of an instinct only remotely, or in some one quality, may start its mechanism and a host of associations bound up with it.  Thus the maternal instinct may be excited by the sight of a baby.  But because a baby is small and delicate, anything small and fine, a tiny book, a toy, a miniature, may arouse it.  The object is then said to be appealing.  The doctrine of association of instinctive and so of endocrine reactions enables us to understand the feeling—­tone that at any moment pervades consciousness as well as its content.

Choices, the psychology of selection of food, color, friends, mates, amusements also become explicable rationally.  For conflicts among the different components of the vegetative system are continuous and inevitable.  If the pressure within a viscus has been heightened, and persists, that is, is not disturbed by some other associated factor or instinct, conduct results to lower the pressure to what it was before the instigator of the tension appeared.  But if another instinct is sparked, or another associated factor comes into play, another focus of increased pressure within the vegetative system is created, with another stream of energy flowing to the brain and demanding an outlet.  This clash of instincts, the struggle between different foci of the vegetative system competing for the possession of the brain, is a common everyday process in conduct.  Which will win means which will will.  And so we have an energetic basis for volition.