[254] Cours, iv, 459. Correspondance de Comte et de John Stuart Mill, p. 219-288. [255] Cours, IV, 450. [256] Cours, IV, 472 sq. [257] Pol. pos., II, 281-3; IV, Appendice, p. 67. [258] Cours, IV, 482-5. CHAPTER IV SOCIAL DYNAMICS For Comte, social dynamics is the chief part of sociology. He tells us that it occupied his attention “in a preponderating and even almost exclusive manner.”[259] This preference is easily explained. In the first place the idea which best distinguishes sociology from biology, the idea of the gradual development of humanity belongs to social dynamics. Then, the method which particularly belongs to sociology, the historical method, applies especially to dynamics. Finally, the very conception of a social science became fixed in Comte’s mind by the discovery of the law of the three states which is a dynamic law. Social dynamics is defined as “the science of the necessary and continuous movement of humanity,”[260] or, more briefly, the science of the laws of progress. Here, as in social statics, and even still more exclusively, a single case is studied, namely, the case of the human species, regarded as a single individual, and considered in the whole of its past and future development. Henceforth, without misunderstanding the distinction between biology and sociology, should we not in the first place seek some of the conditions of social progress in the physical and moral nature of the individual man? This question did not escape Comte, and he says that it would be right to begin a methodical treatise on social science with it. However, he did not expressly deal with the question. He contented himself with indicating “this fundamental instinct which is the complex result of the necessary co-operation between all our natural tendencies, which urges man ceaselessly to ameliorate his condition in all respects, and always to develop the whole of his moral, intellectual, and physical life in every way as much as the system of conditions in which he finds himself placed allows of it.”[261] This indication is completed by the study of the conditions which determined the first efforts of man, when he had to overcome his natural laziness, at the dawn of civilisation. It suffices at least to show the close union which exists in Comte’s thought between social dynamics and psychology. It is true that the sociological laws cannot be _deduced_ from the biological laws. Nothing can replace a direct observation of social phenomena. But the very fact of progress, which is the object of social dynamics, would not exist without the “individual impulses which are its own elements.” I.