There is then no contradiction in affirming the reality of these laws, and in considering at the same time the intervention of human activity in social phenomena as efficacious. As early as 1824 Comte wrote to his friend Valat: “It would be misunderstanding my thought to conclude from it that I forbid all improvement, since, on the contrary, I formally establish that every government must change in consequence of the progress of civilisation, and that it is in no way a matter of indifference that these changes should take place by the mere force of circumstances, or by calculated planes based upon observation. I do not deny the power of political measures, I limit it.”[275] It belongs to social science to determine the limits of the useful action of man upon social phenomena. These limits are narrow enough. Man can only modify, from the static point of view, the intensity, and from the dynamic point of view, the speed of social phenomena. Indeed, here as elsewhere, modifications can only be produced in conformity with laws. To suppose the contrary would be to deny the very existence of these laws. Now, the fundamental law of statics is the intimate solidarity and the mutual dependence of all social elements, at all the moments of their common evolution. There is, therefore, no disturbing influence, whatever its origin may be, which can “cause unsympathetic opposing elements to coexist in a given society.”[276] Rather would it destroy this society. All that is possible is to modify the respective tendencies which indeed coexist in this society, but without causing the appearance or disappearance of any of them. In the same way, from the dynamic point of view, the order of the successive phases of progress is determined by laws. No external influence (nor in particular that of man), could overturn or disturb this order, or “skip” one of the stages. The evolution could only be made more rapid, that is to say, easier. The statesman, infatuated with his power, will perhaps find this a very humble part to play. But, even within these limits, human intervention could still be of capital importance provided that it were directed by science. History confirms these views. In it we never see social phenomena modified by man otherwise than in their intensity, or in their speed. Where we best know their evolution, that is to say, in the social series, which includes the history of the sciences, of the arts, of morals and institutions, the verification of this law is constant. For instance, among the scientific men at Alexandria astronomy stopped at a certain point, because the further development of this science was not compatible with the general conditions of society at that time. And if Montesquieu’s attempt to subject social facts to laws failed, it is because, before sociology, positive biology had first to be founded. Analogous examples abound, and a contrary case has never presented itself.