Of the philosophers who flourished before the rise of the positive doctrine, the greater number assumed as a postulate in the comparative study of man and animals, that there was between them a difference of nature, and not merely one of degree. Whatever fundamental difference be attributed to reason, language, moral sense, religion, etc., the “human kingdom” is conceived for the most part as superior to the animal kingdom and as clearly separated from it. Taking their stand upon an analysis of the present state of the human conscience, those philosophers recognise an order of “moral realities,” to which animals have no access. Thus they give to the science of Man a privileged object which separates it from the group of the natural sciences. The positive method admits neither this postulate, nor the consequences which are drawn from it. In general this method is characterised by the substitution of the objective to the anthropocentric point of view, and also by the substitution of observation to imagination. It does not suddenly change its orientation when it comes to the study of man. The positive method is not therefore concerned with knowing what idea man forms of himself to-day and of his relations with other living beings. Into this idea enter elements of religious and metaphysical origin, whose presence is explained by historical reasons. The question is to observe the nature of man in his _real_ relations with other beings. Man, so considered, at once takes his place again at the top of the zoological scale. The problem will then be set in the following terms: Given that man is included in the animal series, of which he is the highest term, but still a term, to account for the differences which to-day place him so high above the term immediately below him. This is taking the very reverse attitude of nearly all the philosophers, whose main difficulty is to give an account of the likenesses which exist between man and animals. It is the position which Darwin will take in his _Descent of Man_. Comte takes his stand upon two postulates. The first affirms the fundamental identity of the essential functions in man and animals. Since the whole of the moral and intellectual functions constitutes the necessary complement of animal life properly so-called, it would be difficult to conceive that all those functions which are fundamental should not, by this very fact be “common, at various degrees, to all the higher animals, and perhaps even to the entire group of the vertebrata.”[204] The animal functions are as a blossoming out of organic life, destined in the first place to make this life more perfect and more complex: in the same way, the intellectual and moral functions are, originally, as it were, another blossoming out of animal life, and must consequently be found, at least as a possibility, wherever animal life has reached a certain degree of development.