500 THE AMERICAN JOURNAL OF SOCIOLOGY
and by their methodical self-direction that societies manifest their organizing power in its highest degree. And, what is remarkable, this contractualism appears more or less perfectly in every stage of all civilizations, as we shall have occasion to show in our exposition of the great law of homogeneity of social phenomena. Hence, it results that the property of organizing and functioning according to contractual modes is the essence of social aggregates.
We find contractual forms nowhere excepting in social bodies. Contracts may be made in regard to inorganic or organic bodies, but these bodies cannot themselves combine contractually. Thus, aside from the purely quantitative differences observed by Auguste Comte and Herbert Spencer, societies possess a special property, a characteristic mode of activity, which gives rise to equally characteristic forms : a contractual activity and con- tractual forms.
Therefore, sociology is not only quantitatively, but also quali- tatively, distinct from the antecedent sciences ; it has its own domain composed of the co-ordinated ensemble of the special social sciences, an ensemble characterized by particular phenom- ena. As it also has its own method, the historical method in the broadest sense, including statistics, it can and should be organized into a distinct but not independent science.
In the first volume of the Introduction, we proceeded to the analysis of the social phenomena resulting from the combina- tion of their two constituent elements, land and population. After this analysis, we proceeded to the hierarchical classifica- tion. As it stands, this classification is in reality a co-ordination, a first sociological synthesis, at the same time subjective and objective, if we view it from the point of view of knowledge of phenomena and their order, not merely their logical and dogmatic order, but also their natural order. This classifica- tion corresponds, not only to the movement of human thought, which always proceeds from the simplest and most general facts to the most complex and most special, but it is also in harmony with the natural relationship of social phenomena, which become differentiated in proportion as they become organized.
