practical question of applied sexual psychology, and a question of the
first importance. No doubt the sex impulse in men is of great moment from
the social point of view. It is, however, fairly obvious and well
understood. The impulse in women is not only of at least equal moment, but
it is far more obscure. The natural difficulties of the subject have been
increased by the assumption of most writers who have touched it--casually
and hurriedly, for the most part--that the only differences to be sought
in the sexual impulse in man and in woman are quantitative differences. I
have pointed out that we may more profitably seek for qualitative
differences, and have endeavored to indicate such of these differences as
seem to be of significance.

In an Appendix will be found a selection of histories of more or less
normal sexual development. Histories of gross sexual perversion have often
been presented in books devoted to the sexual instinct; it has not
hitherto been usual to inquire into the facts of normal sexual
development. Yet it is concerning normal sexual development that our
ignorance is greatest, and the innovation can scarcely need justification.
I have inserted these histories not only because many of them are highly
instructive in themselves, but also because they exhibit the nature of the
material on which my work is mainly founded.

I am indebted to many correspondents, medical and other, in various parts
of the world, for much valuable assistance. When they have permitted me
to do so I have usually mentioned their names in the text. This has not
been possible in the case of many women friends and correspondents, to
whom, however, my debt is very great. Nature has put upon women the
greater part of the burden of sexual reproduction; they have consequently
become the supreme authorities on all matters in which the sexual emotions
come into question. Many circumstances, however, that are fairly obvious,