It is unnecessary for my present purpose to go further into the voluminous data connected with marriages such as these in all parts of the world. Enough has been said to show that the prohibition of polygamy, under severe penalties by civil and ecclesiastical law, has been due not to any natural instinct against the practice, but to consideration of social well-being. I conclude that equally strict limitations to freedom of marriage might, under the pressure of worthy motives, be hereafter enacted for Eugenic and other purposes. 2. ENDOGAMY, or the custom of marrying exclusively _within_ one’s own tribe or caste, has been sanctioned by religion and enforced by law, in all parts of the world, but chiefly in long settled nations where there is wealth to bequeath and where neighbouring communities profess different creeds. The details of this custom, and the severity of its enforcement, have everywhere varied from century to century. It was penal for a Greek to marry a barbarian, for a Roman patrician to marry a plebeian, for a Hindu of one caste to marry one of another caste, and so forth. Similar restrictions have been enforced in multitudes of communities, even under the penalty of death. A very typical instance of the power of law over the freedom of choice in marriage, and which was by no means confined to Judæa, is that known as the Levirate. It shows that family property and honour were once held by the Jews to dominate over individual preferences. The Mosaic law actually _compelled_ a man to marry the widow of his brother if he left no male issue. (Deuteron. xxv.) Should the brother refuse, “then shall his brother’s wife come unto him in the presence of the elders, and loose his shoe from off his foot, and spit in his face; and she shall answer and say, so shall it be done unto the man that doth not build up his brother’s house. And his name shall be called in Israel the house of him that hath his shoe loosed.” The form of this custom survives to the present day and is fully described and illustrated under the article “Halizah” (= taking off, untying) in the _Jewish Cyclopædia_. Jewish widows are now almost invariably remarried with this ceremony. They are as we might describe it, “given away” by a kinsman of the deceased husband, who puts on a shoe of an orthodox shape which is kept for the purpose, the widow unties the shoe, spits, but now on the _ground_, and repeats the specified words.