It is not, however, the natural materials themselves which have progressed. On the contrary, it is only men who progress, through discovering little by little in nature the conditions which permit them to produce in more and more complex forms, thanks to the labor accumulated in experience. This progress does not consist merely in the sort of progress with which subjective psychology is concerned that is to say, the inner modifications which would be the proper and direct development of the intellect, the reasoning and the thought. Moreover, this inner progress is but a secondary and derived product, in proportion as there is already a progress realized in the artificial foundation which is the sum of the social relations resulting from the forms and the distributions of labor. It is, then, a meaningless affirmation to say that all this is but a simple prolongation of nature, unless one wishes to employ this word in so generic a sense that it no longer indicates anything precise and distinct; that which is not realized by the work of man. History is the work of man in so far as man can create and improve his instruments of labor, and with these instruments can create an artificial environment whose complicated effects react later upon himself, and which by its present state and its successive modifications is the occasion and the condition of his development. There are, then, no reasons for carrying back that work of man which is history to the simple struggle for existence. If this struggle modifies and improves the organs of animals, and if in given circumstances and methods it produces and develops new organs, it still does not produce that continuous, perfected and traditional movement which is the human _processus_. Our doctrine must not be confounded with Darwinism, and it need not invoke anew the conception of a mythical, mystical or metaphorical form of fatalism. If it is true in effect that history rests, before all else, upon the development of technique, that is to say, if it is true that the successive discovery of tools gives rise to the successive distributions of labor, and therewith to the inequalities whose sum total, more or less stable, forms the social organism, it is equally true that the discovery of these instruments is at once the cause and the effect of these conditions and of those forms of the inner life to which, isolating them by psychological abstraction, we give the name of imagination, intellect, reason, thought, etc. By producing successively the different social environment, that is to say, the successive artificial foundations, man has produced himself, and in this consists the serious kernel, the concrete reason, the positive foundation of that which by various fantastic combinations and by a varied logical architecture has suggested to the ideologists the notion of the progress of the human mind.