This last hypothesis will mean, then, that the works of Linnæus, Cuvier, De Blainville, and the two Geoffroys, will be of no value, and that we must commence anew the great work of classification upon the same basis which we wish to adopt in anthropology. Of the two terms of the preceding proposition, the second merits particular consideration. Zoological classification has been created and established by the greatest thinkers of which humanity can boast; even more, independent by its nature from all religious influence, it has been freely done, and without prejudice, as every scientific question ought to be, by means of facts and reasoning. It has not always been so with the works of those who desire that man should be an exception to universal nature, and beyond the limits of the animal kingdom. Zoological classification need not be reformed,--it is that of the genus _Homo_. We touch now on the much discussed and controverted question of species, and at the same time on the question of the origin of man. We do not believe, as many eminent men have done, that this origin must eternally be concealed, that man will never be permitted to tear the veil from this statue of Isis. Let it suffice us to say that we are about to enter on slippery ground, where we shall only find as few resting places as the stones of a ford half destroyed by a torrent. And since we shall only find here and there the fragile aid of one hypothesis against so many others, in order to assist the consequents of our reasonings, is it a reason for drawing back? We do not think so. Every period of a science has its own tendency; at given moments the efforts of all tend involuntarily towards one sole end,--one question absorbs all, and all partial solutions tend to the same general solution. At the present day, the great question in natural history is that of species; inquiries are ardently pursued, and materials are produced from every side,--opinions are mooted, and objections raised. We have only to call attention on this point to the works of Isidore Geoffroy, Morton, Nott, Godron, Broca,[285] Darwin, Fée, etc. The question of spontaneous generation is but a phase of the same discussion, an episode in the work of the birth of time.