elation to Marriage_, vol. i, p. 213), "I can hardly think of
any combination which does not figure among my case-notes as
having been practiced by my patients." We must not too hastily
conclude that such variations are due to vicious training. That
is far from being the case. They often occur naturally and
spontaneously. Freud has properly pointed out (in the second
series of his _Beitraege zur Neurosenlehre_, "Bruchstueck" etc.)
that we must not be too shocked even when the idea of _fellatio_
spontaneously presents itself to a woman, for that idea has a
harmless origin in the resemblance between the penis and the
nipple. Similarly, it may be added, the desire for
_cunnilinctus_, which seems to be much more often latently
present in women than is the desire for its performance in men,
has a natural analogy in the pleasure of suckling, a pleasure
which is itself indeed often erotically tinged (see vol. iv of
these _Studies_, "Sexual Selection in Man," Touch, Sect. III).

Every variation in this matter, remarks Remy de Gourmont
(_Physique de l'Amour_, p. 264) partakes of the sin of luxury,
and some of the theologians have indeed considered any position
in coitus but that which is usually called normal in Europe as a
mortal sin. Other theologians, however, regarded such variations
as only venial sins, provided ejaculation took place in the
vagina, just as some theologians would permit _irrumatio_ as a
preliminary to coitus, provided there was no ejaculation. Aquinas
took a serious view of the deviations from normal intercourse;
Sanchez was more indulgent, especially in view of his doctrine,
derived from the Greek and Arabic natural philosophers, that the
womb can attract the sperm, so that the natural end may be
attained even in unusual positions.

Whatever difference of opinion there may have been among ancient
theologians, it is well recognized by modern physicians that
variations from the ordinary method of coitus are desirable in
special cases. Thus Kisch points out (_Sterilitaet des Weibes_, p.
107) that in some cases it is only possible for the woman to
experience sexual excitement when coitus takes place in the
lateral position, or in the _a posteriori_ position, or when the
usual position is reversed; and in his _Sexual Life of Woman_,
also, Kisch recommends several