If we break up one continuous series, and compare together the two first terms with two of the fragments of the series, they will in reality appear entirely distinct; in fact, almost impossible to be connected with one common type. But, if we compare the last term of one of these partial series with the first term of the following, then the differences are blended, because the transformations do not happen to hide the parts so much that one cannot recognise their fundamental unity. We discover, for example, that in the animal series, such a crustacean is almost a mollusk, such a reptile, such a mammal, almost a bird.[32] Differences are extinguished; those beings which were said to be most distant have become almost allied one to the other. We can only perceive one continuous series; so much so, indeed, that even where there are any unfilled spaces, or missing links, we consider ourselves almost justified in declaring the past existence (or the future one?) of some intermediate animal. As for ourselves, the series of beings given by Bonnet and Leibnitz, so far as regards any ulterior phenomenon, resulting from the observation of beings who have not been of necessity created in this order, is true not only of the physical, but also of the intellectual world. Shall we desire to know what man has in common with the ape--what distance there is between the one and the other,--let us no longer put _ourselves_ on the stage, we who are privileged so to do; let us descend boldly the steps of the human ladder, and let us see what we shall find as we do so. Examples are not wanting of races placed so low, that they have quite naturally appeared to resemble the ape tribe. These people, much nearer than ourselves to a state of nature, deserve on that account every attention on the part of the anthropologist and the linguist, who may both discover, by their means, problems otherwise difficult or impossible to be solved. It is because we have not studied the psychological characters of these races, that we have fallen into such strange mistakes. What will become of all those superb theories concerning this superior intelligence of man, so entirely independent and disengaged from the world, on which so much praise is conferred? What will become of the unity of the human species, if we can prove that certain races are not a whit more intelligent than certain animals, and have no more idea of a moral world or of religion than they themselves have?