Three secondary factors, race, climate, and man’s political action especially modify progress, in the measure which has just been indicated. In the present state of science it is impossible to arrange them in the order of their importance. Montesquieu, made too much of climates: others have made too much of races.[277] Those elements of social evolution have not yet been studied by the positive method. Until the foundation of social dynamics their part was, of necessity, wrongly conceived. It was not known that the essential law, the law of the three states, is independent of these secondary factors, whilst on the contrary the secondary factors can only act in conformity with this law, without ever suspending it. In order that the modifications which they produce should become intelligible, it was necessary that the normal type of evolution should first be known. To study the influence of climates and of races before first possessing the general laws of social dynamics, was, almost, to pretend to establish pathology without having first constituted physiology. As to man’s political action, it too has been wrongly understood. In the absence of a positive conception of social phenomena, some denied the efficacy of this action, others exaggerated it. When it was used in the direction of progress, it almost necessarily appeared to be the principal cause of the results which social evolution would have brought about in any case. The illusion was all the more inevitable from the fact that social forces are always personified in individuals. On the other hand, how often have the most vigorous political efforts only been successful for a day, because the general evolution of society was proceeding in the contrary direction! So long as the theological and metaphysical period lasts, man does not hesitate to ascribe to himself an almost boundless action upon natural phenomena. Having reached the positive period, he knows that phenomena are only, modifiable within certain limits, determined by their laws, and that he can only aspire to relative results. Once positive sociology is established it wholly transforms the familiar idea of political art. But because it entertains less great and less gratifying ambitions, this art will only be all the more effective. Compare what medicine and surgery are able to do to-day for the good of the sick with what they could do before chemistry and biology became positive sciences! But, it is said, admitting that man can modify social phenomena, what reason has he to interfere with them, since progress takes place of itself? Why not allow the natural evolution which most certainly realises it to work itself out?