We shall carefully, then, avoid entering into any controversy touching the dogmas of one religion or the other; we shall not contest the authority of the Scriptures, whatever they may be, Hebrew, Christian, Arabic, or Buddhist; we have put them on one side, and that is all.[20] Descartes has truly observed that every scientific question ought to be examined, even those which are most superstitious and most false, “so as to recognise their just value, and to guard against being deceived by them.”[21] One may be free to consider this essay as an attempt of that kind. We shall be praised or blamed: we have been so already. We have, for our comfort, the conscientious feeling of having no other object before our eyes but an inquiry into truth,--the truth, the common end towards which the power of every man who believes in progress should tend. “Where truth reigns,” says M. Chevreul, “no disputes or discussions are possible.”[22] The reign of truth is the reign of concord amongst mankind. It is the golden age. CHAPTER I. THE HUMAN KINGDOM. Above inorganic matter, plants, and animals, is placed Man. Here, without any doubt, man is indeed the first of the organisms, when one tries to place in linear series all those which move on our planet. It is, also, not his _relative_ position in the living world that it is difficult to discover; it is what we may call his _true place_. What is, in other terms, the value of the differences which separate man from other mammalia? and at what distance is he from the animal that immediately follows him in this linear series which we are supposing? To examine what man is with respect to the highest orders of mammalia, and in a more general manner, to animals, is the primordial question which presents itself in anthropology. It seems at first sight that it would suffice, in order to settle it, to throw a glance on this complete body, formed of the same anatomical elements, absolutely submitted to the same exigences of development, nutrition, and reproduction, as animals. Ought not all this to make us think that we were not altogether made of so immaterial a substance as the philosophers have generally been satisfied to believe? This has not been the case. Two systems--two theories, are before us. The one pretends that man is but the first among animals, that he is _similar_ to them in the clear and precise sense in which this term is taken in geometry, designing qualities, which may differ _ad infinitum_, but which still may be comparable.