Under the influence of Christianity, assisted by the barbarians, a vast change passed gradually over the world. The vice we are considering was probably more rare; it certainly assumed less extravagant forms, and it was screened from observation with a new modesty. The theory of morals had become clearer, and the practice was somewhat improved. The extreme grossness of literature had disappeared, and the more glaring violations of marriage were always censured and often repressed. The penitential discipline, and the exhortations of the pulpit, diffused abroad an immeasurably higher sense of the importance of purity than Pagan antiquity had known. St. Gregory the Great, following in the steps of some Pagan philosophers,(758) strenuously urged upon mothers the duty of themselves suckling their children; and many minute and stringent precepts were made against extravagances of dress and manners. The religious institutions of Greece and Asia Minor, which had almost consecrated prostitution, were for ever abolished, and the courtesan sank into a lower stage of degradation. Besides these changes, the duty of reciprocal fidelity in marriage was enforced with a new earnestness. The contrast between the levity with which the frailty of men has in most ages been regarded, and the extreme severity with which women who have been guilty of the same offence have generally been treated, forms one of the most singular anomalies in moral history, and appears the more remarkable when we remember that the temptation usually springs from the sex which is so readily pardoned; that the sex which is visited with such crushing penalties is proverbially the most weak; and that, in the case of women, but not in the case of men, the vice is very commonly the result of the most abject misery and poverty. For this disparity of censure several reasons have been assigned. The offence can be more surely and easily detected, and therefore more certainly punished, in the case of women than of men; and, as the duty of providing for his children falls upon the father, the introduction into the family of children who are not his own is a special injury to him, while illegitimate children who do not spring from adultery will probably, on account of their father having entered into no compact to support them, ultimately become criminals or paupers, and therefore a burden to society.(759) It may be added, I think, that several causes render the observance of this virtue more difficult for one sex than for the other; that its violation, when every allowance has been made for the moral degradation which is a result of the existing condition of public opinion, is naturally more profoundly prejudicial to the character of women than of men; and also that much of our feeling on these subjects is due to laws and moral systems which were formed by men, and were in the first instance intended for their own protection.