I am not aware that the Greeks were greatly concerned with the moral justification of prostitution.  They had not allowed it to assume very offensive forms and for the most part they were content to accept it.  The Romans usually accepted it, too, but, we gather, not quite so easily.  There was an austerely serious, almost Puritanic, spirit in the Romans of the old stock and they seem sometimes to have felt the need to assure themselves that prostitution really was morally justifiable.  It is significant to note that they were accustomed to remember that Cato was said to have expressed satisfaction on seeing a man emerge from a brothel, for otherwise he might have gone to lie with his neighbor’s wife.[193]

The social necessity of prostitution is the most ancient of all the arguments of moralists in favor of the toleration of prostitutes; and if we accept the eternal validity of the marriage system with which prostitution developed, and of the theoretical morality based on that system, this is an exceedingly forcible, if not an unanswerable, argument.

The advent of Christianity, with its special attitude towards the “flesh,” necessarily caused an enormous increase of attention to the moral aspects of prostitution.  When prostitution was not morally denounced, it became clearly necessary to morally justify it; it was impossible for a Church, whose ideals were more or less ascetic, to be benevolently indifferent in such a matter.  As a rule we seem to find throughout that while the more independent and irresponsible divines take the side of denunciation, those theologians who have had thrust upon them the grave responsibilities of ecclesiastical statesmanship have rather tended towards the reluctant moral justification of prostitution.  Of this we have an example of the first importance in St. Augustine, after St. Paul the chief builder of the Christian Church.  In a treatise written in 386 to justify the Divine regulation of the world, we find him declaring that just as the executioner, however repulsive he may be, occupies a necessary place in society, so the prostitute and her like, however sordid and ugly and wicked they may be, are equally necessary; remove prostitutes from human affairs and you would pollute the world with lust:  “Aufer meretrices de rebus humanis, turbaveris omnia libidinibus."[194] Aquinas, the only theological thinker of Christendom who can be named with Augustine, was of the same mind with him on this question of prostitution.  He maintained the sinfulness of fornication but he accepted the necessity of prostitution as a beneficial part of the social structure, comparing it to the sewers which keep a palace pure.[195] “Prostitution in towns is like the sewer in a palace; take away the sewers and the palace becomes an impure and stinking place.”  Liguori, the most influential theologian of more modern times, was of the like opinion.