The demand for sex gratification, because of its enormous driving force and the emotional disturbances connected with it, offers a peculiarly acute instance of the difficulties brought about in the control of man's native endowment in his own best interest. While the production of offspring is its chief biological utility, satisfaction of the sex instinct itself is stimulated in human beings quite apart from considerations of the desirability or undesirability of offspring. Since the sex instinct is at once so deep-rooted and intense a driving force in human action, and its consequences of such crucial importance to both those directly involved and to the group as a whole, societies have, through law and custom and tradition, built up elaborate codes for its control. In civilized society the free operation of this instinct is checked in a thousand ways. But, as in the case of other primitive motives to action, the sex instinct, obvious as are the disasters of disease and disorganization which follow as consequences of its uncontrolled indulgence, cannot altogether be repressed. It is generally recognized that in men and animals alike the sex impulse is apt to manifest itself in very vigorous and sustained efforts toward its natural end; and that in ourselves it may determine very strong desires, in the control of which all the organized forces of the developed personality, all our moral sentiments and ideals, and all the restraining influences of religion, law, custom and convention too often are confronted with a task beyond their strength.[1] [Footnote 1: McDougall: _Social Psychology_, 11th ed., pp. 399-400.] There is considerable agreement among students of the subject that the emotional energies aroused in connection with the sex instinct may be drained off into other channels, and serve to quicken and sustain both artistic creation and appreciation and social and religious enthusiasms of various kinds. And the sex instinct, as we shall find in our discussion of Racial Continuity (see p. 243) is the basis of the family.