To the man coitus must be in some slight degree pleasurable or it cannot take place at all. To the woman the same act which, under some circumstances, in the desire it arouses and the satisfaction it imparts, will cause the whole universe to shrivel into nothingness, under other circumstances will be a source of anguish, physical and mental. This is so to some extent even in the presence of the right and fit man. There can be no doubt whatever that the mucus which is so profusely poured out over the external sexual organs in woman during the excitement of sexual desire has for its end the lubrication of the parts and the facilitation of the passage of the intromittent organ. The most casual inspection of the cold, contracted, dry vulva in its usual aspect and the same when distended, hot, and moist suffices to show which condition is and which is not that ready for intercourse, and until the proper condition is reached it is certain that coitus should not be attempted. The varying sensitiveness of the female parts again offers difficulties. Sexual relations in women are, at the onset, almost inevitably painful; and to some extent the same experience may be repeated at every act of coitus. Ordinary tactile sensibility in the female genitourinary region is notably obtuse, but at the beginning of the sexual act there is normally a hyperesthesia which may be painful or pleasurable as excitement culminates, passing into a seeming anesthesia, which even craves for rough contact; so that in sexual excitement a woman normally displays in quick succession that same quality of sensibility to superficial pressure and insensibility to deep pressure which the hysterical woman exhibits simultaneously. Thus we see that a highly important practical result follows from the greater complexity of the sexual apparatus in women and the greater difficulty with which it is aroused. In coitus the orgasm tends to occur more slowly in women than in men. It may easily happen that the whole process of detumescence is completed in the man before it has begun in his partner, who is left either cold or unsatisfied. This is one of the respects in which women remain nearer than men to the primitive stage of humanity. In the Hippocratic treatise, _Of Generation_, it is stated that, while woman has less pleasure in coitus than man, her pleasure lasts longer. (_Oeuvres d'Hippocrate_, edition Littré, vol. vii, p. 477.)