is therefore necessary to gather together the biological data which are
available from technical experimentation and medical research, in order
that its social implications may be utilized to show the obsoleteness of
this older and unscientific statement of the sex problem in society.

In order to have a thoroughly comprehensive survey of the institutions
connected with sexual relationships and the family and their entire
significance for human life, it is also necessary to approach them from
the ethnological and psychological points of view. The influence of the
primitive sex taboos on the evolution of the social mores and family
life has received too little attention in the whole literature of sexual
ethics and the sociology of sex. That these old customs have had an
inestimable influence upon the members of the group, modern psychology
has recently come to recognize. It therefore seems advantageous to
include these psychological findings in the same book with the
discussion of the sex taboos and other material with which it must so
largely deal.

These fields--biology, ethnology, and psychology--are so complicated and
so far apart technically, although their social implications are so
closely interwoven, that it has seemed best to divide the treatment
between three different writers, each of whom has devoted much study to
his special phase of the subject. This leads to a very simple
arrangement of the material. The first part deals with the physical or
biological basis of the sex problem, which all societies from the most
primitive to the most advanced have had and still have to build upon.
The second part deals with the various ideas man has developed in his
quest for a satisfactory adaptation of this physical basis to his own
requirements. Part three attempts to analyze the effect of this long
history of social experimentation upon the human psyche in its modern