hysiological conditions
that are favorable for fertilization. In fact, spontaneous
physiological demands play in civilized human life a minor part in
initiating sexual excitement. The reason why some humans seem to have
unusual sexual intensity is not so much a matter of exceptionally
strong sexuality as of susceptibility to the numerous sexual stimuli
with which modern life abounds. For this reason, a man who has formed
lewd memory associations is more susceptible to sexual stimulations,
_e.g._, by obscene pictures, vulgar words, unusual dress or actions of
women, close physical association as in dancing, and certain forms of
music. It is not at all uncommon that individuals who are
hyper-sensitive to sexually suggestive stimuli are really functionally
weak.

[Sidenote: Intelligent control only.]

It follows from the facts outlined above that instinctive control of
sexual actions applies to animals but not to human life. On the
contrary, human control must be on the basis of intelligent choice.
This means the greatest task of human life, for it requires voluntary
control of instinctive demands which are intensified by numerous
stimuli or temptations that are exclusively human. No wonder that
natural sex hunger left uncontrolled leads human beings to excesses and
degradation that no species of animals with their guiding instincts
could possibly reach.

[Sidenote: Individual responsibility.]

The absence from human life of any instinctive control of sexual
actions leaves a great responsibility on each individual whose natural
desires lead impulsively and insistently towards sexual union and must
be restrained, controlled, and directed by voluntary choice. In short,
all individuals who are intelligent beings are personally responsible
for voluntary control of their sexual desires with reference to the
ethical, social, and eugenic interests and rights of all other
individuals now and in the future.

[Sidenote: Sexual knowledge necessary.]

With such an understanding of instincts in relation to human sexual
actions, we cannot wonder that the old policy of mystery has failed so
completely. Since human beings are left to control the most powerful
appetite by intelligence, it is evident that a policy based on silence,
ignorance, and mystery must fail. The only safe and sure road to the
needed control of sexual actions is to be found in knowledge, and the
widespread recognition of this fact has led to the new movement f