The Romans had also their houses of prostitution or lupanari, public or private, as well as free prostitutes. In the Middle Ages, prostitution developed especially after the Crusades. It is related that the Council of Constance attracted fifteen hundred prostitutes to this town. Prostitutes followed the armies everywhere. In India, young girls give themselves to the priests, who are the representatives of God and enjoy great honors. Under the name of Temple girls, the girls of the flower boats of China are really prostitutes. It is the same with the puzes of Java, the girls in the Japanese tea-houses, etc. In some civilized states, certain refined and intelligent prostitutes have always obtained great honors and high favors, only charging high prices, and ending by substituting for prostitution the pecuniary exploitation of rich men whom they have seduced. Concubinage may be more or less free. The concubines were formerly often slaves, possessed by men in high positions, in addition to their wives. At the present day the omnipotence of money produces almost analogous results. Free concubinage, in which sexual intercourse between the two contracting parties is absolutely free and more or less independent of pecuniary questions, is very different and of a higher moral character. It has also existed in antiquity in various forms. The Greek hetairas were concubines of high position, no doubt prostitutes of a kind and giving themselves for money; but they became the friends or companions of great men. Living in luxury, especially at the time of Pericles and later, several of them became celebrated; statues were raised to them and they became the concubines of kings. Phryne served as the model for the statue of Venus, and offered to restore the halls of the Thebeans at her own expense. Thais was the mistress of Alexander and gave heirs to the throne. The neglected education of the Greek wives caused the intellectual accomplishments of the hetairas to shine by contrast. The whole question regarding the Greek customs is summed up in a few words by Demosthenes: "We marry wives in order to have legitimate children and a faithful guardian for our household; we have concubines for our daily service, and hetairas for the enjoyment of love." In some countries, such as Japan, the children of concubines are considered by the husbands as legitimate, and have the same rights as those of his wife; this gives concubinage the character of marriage of the second rank. In modern times hetairas are not wanting. Under the title of courtesans and mistresses, we find them everywhere as the favorites of kings and nobles, as mistresses of men in high positions, and often playing the part of vampires in all classes of society. On the other hand, women of high position or wealth have also their favorites, whom we may call male hetairas. Certain female members of royal families have at all times furnished examples of this kind.