A dogma supported by the authority of the Book which is held in almost equal respect by Christians, Jews and Mussulmans, has long referred the origin of all men without opposition to a single father and mother. Nevertheless, the first blow aimed at this ancient belief was founded upon the same book. In 1655 La Peyrère, a Protestant gentleman in Condé’s army, interpreting to the letter the two narratives of the creation contained in the Bible as well as various particulars in the history of Adam and of the Jewish nation, attempted to prove that the latter alone were descended from Adam and Eve; that they had been preceded by other men who had been created at the same time as the animals in all parts of the habitable globe; that the descendants of these _Preadamites_ were identical with the _Gentiles_, who were always so carefully distinguished from the Jews. Thus we see that polygenism generally regarded as the result of _Free Thought_ was biblical and dogmatic in origin. La Peyrère attacked the Adamic dogma in the name of the respect due to the text of a sacred Book. The philosophers of the eighteenth century spoke in the name of Science and Reason. It is to them that the school of Polygenists in reality owe their origin. But it is easy to see that the greater number of them were only guided in their writings by a controversial spirit, their chief aim was the destruction of a dogma. Unfortunately, the same prepossession appears in too many works published in our own day. On the other hand certain monogenists are guilty of seeking in religious doctrines arguments in favour of their theory, and anathematising their adversaries in the name of dogma. Social and political prejudices in addition to dogmatic and anti-dogmatic prejudices have helped to make still more obscure a question already very difficult in itself. In the United States in particular the advocates of slavery and its opponents have often fought upon this ground. Further still in 1844 Mr. Calhoun, Minister of Foreign Affairs, when replying to the representations made to him by France and England on the subject of slavery, did not hesitate to defend the institutions of his country by urging the radical differences, which, according to him, separated the Negro from the White man.