In connection with the late evolution of the sexual emotions in women reference may be made to what is usually termed "old maid's insanity," a condition not met with in men. In these cases, which are not, indeed, common, single women who have led severely strict and virtuous lives, devoting themselves to religious or intellectual work, and carefully repressing the animal side of their natures, at last, just before the climacteric, experience an awakening of the erotic impulse; they fall in love with some unfortunate man, often a clergyman, persecute him with their attentions, and frequently suffer from the delusion that he reciprocates their affections. When once duly aroused, there cannot usually be any doubt concerning the strength of the sexual impulse in normal and healthy women. There would, however, appear to be a distinct difference between the sexes at this point also. Before sexual union the male tends to be more ardent; after sexual union it is the female who tends to be more ardent. The sexual energy of women, under these circumstances, would seem to be the greater on account of the long period during which it has been dormant. Sinibaldus in the seventeenth century, in his _Geneanthropeia_, argued that, though women are cold at first, and aroused with more difficulty and greater slowness than men, the flame of passion spreads in them the more afterward, just as iron is by nature cold, but when heated gives a great degree of heat. Similarly Mandeville said of women that "their passions are not so easily raised nor so suddenly fixed upon any particular object; but when this passion is once rooted in women it is much stronger and more durable than in men, and rather increases than diminishes by enjoying the person of the beloved." (_A Modest Defence of Public Stews_, 1724, p. 34.) Burdach considered that women only acquire the full enjoyment of their general strength after marriage and pregnancy, while it is before marriage that men have most vigor. Schopenhauer also said that a man's love decreases with enjoyment, and a woman's increases. And Ellen Key has remarked (_Love and Marriage_) that "where there is no mixture of Southern blood it is a long time, sometimes indeed not till years after marriage, that the senses of the Northern women awake to consciousness."