choose the social and eschew the biological functions.

Racial degeneration is the result. Recorded history is one succession of
barbarous races, under strong, primitive breeding conditions, swamping
their more civilized, individualized neighbours, adopting the dysgenic
ways of civilization and then being swamped in their turn by barbarians.
This is especially pronounced in our own times because popularized
biological and medical knowledge makes it possible for a tremendous
class of the most successful and enlightened to avoid reproduction
without foregoing sex activity.

In primitive groups, a "moral" control which kept all women at
reproduction was neither eugenic nor dysgenic unless accompanied by
systematic destruction of the least fit children. By "moral" control is
meant the use of taboo, prejudice, religious abhorrence for certain acts
and the like. The carefully nurtured moral ideas about sex and
reproduction simply represent the system of coercion which groups have
found most effective in enforcing the division of reproductive and other
activities among the individual members. When this social machinery grew
up, to regulate sexual activity was in general to regulate
reproduction. The natural sex desire proved sufficiently powerful and
general to still seek its object, even with the group handicaps and
regulations imposed to meet the reproductive necessity. But
contraceptive knowledge, etc., has now become so general that to
regulate sex activity is no longer to regulate reproduction. The taboo
or "moral" method of regulation has become peculiarly degenerating to
race quality, because the most intelligent, rationalized individuals are
least affected by it.

There is no turning back to control by ignorance. Even theoretically,