The actual period of the menstrual flow, at all events the first two or three days, does not, among European women, usually appear to show any heightening of sexual emotion.[108] This heightening occurs usually a few days before, and especially during, the latter part of the flow, and immediately after it ceases.[109] I have, however, convinced myself by inquiry that this absence of sexual feeling during the height of the flow is, in large part, apparent only.  No doubt, the onset of the flow, often producing a general depression of vitality, may tend directly to depress the emotions, which are heightened by the general emotional state and local congestion of the days immediately preceding; but among some women, at all events, who are normal and in good health, I find that the period of menstruation itself is covered by the period of the climax of sexual feeling.  Thus, a married lady writes:  “My feelings are always very strong, not only just before and after, but during the period; very unfortunately, as, of course, they cannot then be gratified”; while a refined girl of 19, living a chaste life, without either coitus or masturbation, which she has never practiced, habitually feels very strong sexual excitement about the time of menstruation, and more especially during the period; this desire torments her life, prevents her from sleeping at these times, and she looks upon it as a kind of illness.[110] I could quote many other similar and equally emphatic statements, and the fact that so cardinal a relationship of the sexual life of women should be ignored or denied by most writers on this matter, is a curious proof of the prevailing ignorance.[111]

This ignorance has been fostered by the fact that women, often disguise even to themselves the real state of their feelings.  One lady remarks that while she would be very ready for coitus during menstruation, the thought that it is impossible during that time makes her put the idea of it out of her mind.  I have reason to think that this statement may be taken to represent the real feelings of very many women.  The aversion to coitus is real, but it is often due, not to failure of sexual desire, but to the inhibitory action of powerful extraneous causes.  The absence of active sexual desire in women during the height of the flow may thus be regarded as, in part, a physiological fact, following from the correspondence of the actual menstrual flow to the period of pro-oestrum, and in part, a psychological fact due to the aesthetic repugnance to union when in such a condition, and to the unquestioned acceptance of the general belief that at such a period intercourse is out of the question.  Some of the strongest factors of modesty, especially the fear of causing disgust and the sense of the demands of ceremonial ritual, would thus help to hold in check the sexual emotions during this period, and when, under the influence of insanity, these motives are in abeyance, the coincidence of sexual desire with the menstrual flow often becomes more obvious.[112]