associated with neuropathic states, as well as with anomalies of the genital organs, or general troubles of nutrition, and is usually acquired. Some authors attribute great importance to amenorrhea in this connection; one investigator has found that in 4 out of 14 cases of absolute amenorrhea sexual feeling was absent. Löwenfeld, again (_Sexualleben und Nervenleiden_), referring to the common misconception that nervous disorder is associated with increased sexual desire, points out that nervously degenerate women far more often display frigidity than increased sexual desire. Elsewhere (_Ueber die Sexuelle Konstitution_) Löwenfeld says it is only among the upper classes that sexual anesthesia is common. Campbell Clark, also, showed some years ago that, in young women with a tendency to chlorosis and a predisposition to insanity, defects of pelvic and mammary development are very prevalent. (_Journal of Mental Science_, October, 1888.) As regards the older medical authors, Schurig (_Spermatologia_, 1720, p. 243, and _Gynæcologia_, 1730, p. 81) brought together from the literature and from his own knowledge cases of women who felt no pleasure in coitus, as well as of some men who had erections without pleasure. There is, however, much uncertainty as to what precisely is meant by sexual frigidity or anesthesia. All the old medical authors carefully distinguish between the heat of sexual desire and the actual presence of pleasure in coitus; many modern writers also properly separate _libido_ from _voluptas_, since it is quite possible to experience sexual desires and not to be able to obtain their gratification during sexual intercourse, and it is possible to hold, with Mantegazza, that women naturally have stronger sexual impulses than men, but are more liable than men to experience sexual anesthesia. But it is very much more difficult than most people seem to suppose, to obtain quite precise and definite data concerning the absence of either _voluptas_ or _libido_ in a woman. Even if we accept the statement of the woman who asserts that she has either or both, the statement of their absence is by no means equally conclusive and final. As even Adler--who discusses this question fully and has very pronounced opinions about it--admits, there are women who stoutly deny the existence of any sexual feelings until such feelings are actually discovered.[158] Some of the most marked characteristics of the sexual impulse in women, moreover,--its association with modesty, its comparatively late development, its seeming passivity, its need of stimulation,--all combine to render difficult the final pronouncement that a woman is sexually frigid. Most significant of all in this connection is the complexity of the sexual apparatus in women and the corresponding psychic difficulty--based on the fundamental principle of sexual selection--of finding a fitting mate.