' or 'The Sexual Life of the Child,' who finds
pleasant diversion in the treatment of sex-behavior in the ordinary
novel, newspaper, or play.

On the whole, the gain from giving earnest men and women the facts they
need, seems likely to outweigh by much the harm done to such light minds
as will be misled, or to such sentimental minds as will be wounded, by
enlightenment about sex. No harm will be done to those men and women
whose interest in the welfare of children makes them eager to face every
problem that it involves, and whose faith in the ideal possibilities of
love between the sexes is too well-grounded to be disturbed by the facts
of its natural history.

EDWARD L. THORNDIKE.

MAY, 1912.

PREFACE

The number of books and essays dealing with sexual topics published
during recent years is by no means small; but although some of the works
in question have added considerably to our knowledge, the advance of
sexual science as a whole has not been proportionate to the extent of
these contributions. The reason is that insufficient attention has been
paid to special problems; and the majority of writers have either
repeated what has already been said by another, in identical or
equivalent words, or else they have published comprehensive treatises on
the sexual life, which may, perhaps, be of interest to the laity, but do
not in any way enrich our science. Further advances in our knowledge of
the sexual life can be effected only by the investigation of special
problems. Such work is, indeed, laborious; but that it is also fruitful,
has been clearly shown, not only in the first instance by von
Krafft-Ebing, but more recently, above all, by Havelock Ellis, whose
special studies have contributed more to the advance of sexual science
than the work of dozens of other writers.

The recognition of the need for specialised investigations has led me,
in this province of scientific work as in other departments, to devote
myself to the elucidation of certain definite problems. For several
reasons I determined to study the sexual life of the child. In the first
place, I believe that an advance in our knowledge of the sexual life of
the child will indirectly enrich our knowledge also of the sexual life
of the adult. In order to understand the sexual life, the gradual
development of that life must be recognised, and for this purpose it is
essential that we should study the sexual life of the child. Moreover,
the modern