[In supervising the publication of this work, I have thought proper to omit, in this place, a portion of the translation, because containing ideas and suggestions which--though they might be novel to a French public--have often been laid before English readers, and as often proven untenable. This omission, however, embraces no essential feature of the book, no link of the chain of argumentation. It extends no further than a digressional attempt of the author to account for the diversities observable in the various branches of the human family, by imagining the existence of cosmogonal causes, long since effete, but operating for a time soon after the creation of man, when the globe was still in a nascent and chaotic state. It must be obvious that all such speculations can never bridge over the wide abyss which separates _hypotheses_ from _facts_. They afford a boundless field for play to a fertile imagination, but will never stand the test of criticism. Even if we were to suppose that such causes had effected diversities in the human family in primeval times, the types thus produced must all have perished in the flood, save that to which Noah and his family belonged. If these writers, however, should be disposed to deny the universality of the deluge, they would evidently do greater violence to the language of Holy Writ, than by at once supposing a plurality of origins for mankind. The legitimate field of human science is the investigation of the laws _now_ governing the material world. Beyond this it may not go. Whatever is recognized as not coming within the scope of action of these laws, belongs not to its province. We have proved, and I think it is generally admitted, that the actual varieties of the human family are _permanent_; that there are no causes _now in operation_, which can transform them. The investigation of those causes, therefore, cannot properly be said to belong to the province of human science. In regard to their various systems of classification, naturalists may be permitted to dispute about unity or plurality of species, because the use of the word species is more or less arbitrary; it is an expedient to secure a convenient arrangement. But none, I hope, presume ever to be able to fathom the mysteries of Creative Power--to challenge the fiat of the Almighty, and inquire into his _means_.--H.]