y
become evident from behind as elements which have been made functional
through experience, and a discussion of these would lead far beyond the
working sphere of psychoanalysis.

A similar connection determines the relation between ontogenesis and
phylogenesis. Ontogenesis may be considered as a repetition of
phylogenesis insofar as the latter has not been varied by a more recent
experience. The phylogenetic disposition makes itself visible behind the
ontogenetic process. But fundamentally the constitution is really the
precipitate of a former experience of the species to which the newer
experience of the individual being is added as the sum of the occasional
factors.

Beside its thoroughgoing dependence on psychoanalytic investigation I
must emphasize as a character of this work of mine its intentional
independence of biological investigation. I have carefully avoided the
inclusion of the results of scientific investigation in general sex
biology or of particular species of animals in this study of human
sexual functions which is made possible by the technique of
psychoanalysis. My aim was indeed to find out how much of the biology of
the sexual life of man can be discovered by means of psychological
investigation; I was able to point to additions and agreements which
resulted from this examination, but I did not have to become confused if
the psychoanalytic methods led in some points to views and results which
deviated considerably from those merely based on biology.

I have added many passages in this edition, but I have abstained from
calling attention to them, as in former editions, by special marks. The
scientific work in our sphere has at present been retarded in its
progress, nevertheless some supplements to this work were indispensable
if it was to remain in touch with our newer psychoanalytic literature.

VIENNA, October, 1914.

I

THE SEXUAL ABERRATIONS[1]

The fact of sexual need in man and animal is expressed in biology by the
assumption of a "sexual impulse." This impulse is made analogous to the
impulse of taking nourishment, and to hunger. The sexual expression
corresponding to hunger not being found colloquilly, science uses the
expression "libido."[2]

Popular conception makes definite assumptions concerning the nature and
qualities of this sexual impulse. It is supposed to be absent during
childhood and to commence about the time of and in connection with the
maturing process of pu