of knowledge was almost instinctive, and of such a nature as gregarious animals possess, or it was at least a product of gradual experience. For a long time social organization was not a subject of study like physical phenomena. Politics was the first social science to develop, if we may except ethics, which in its origin was connected with religion or philosophy, and was hardly an inductive social science. An interest in politics did not arise until different forms of social organization appeared and could be readily compared. A mere aggregation of people did not stimulate a study of politics, nor did more complicated organizations as long as they all rested on force. But when a change in social organization appeared possible, when different forms could be compared, and some were seen to be more efficient than others, social organization became an object of study. Under such conditions appeared Plato's "Republic," Aristotle's "Politics" and Machievelli's "Prince." Economics and other social sciences followed politics, but so difficult and complicated are the laws of association, that even with the present facilities for investigation, a general science of sociology can hardly be said to be established. The three comprehensive groups of sciences here outlined, seem, therefore, to have appeared in the order given in accordance with men's interests and the complexity of the phenomena to be studied; though it must be admitted that the subdivisions of the sciences did not develop according to their complexity alone. The additional influence of the immediate needs of mankind is strong enough to disturb materially Comte's theory of their historical development.
It is possible now to go a step farther and show that the growth of one group of sciences prepares the way both directly and indirectly for the growth of another group. The direct effect of the advance of one science upon others is a well-recognized fact and this influence is not by any means always in the direct order of their serial development, according to Comte's classification, but is frequently in the inverse order. A knowledge of physics has helped to advance astronomy as much as it has chemistry. This form of the interdependence of the sciences need not be enlarged upon.
The sciences have a less direct effect upon each other through the alteration of social conditions and the change of men's interests. Thus the earlier sciences have in a sense prepared the way for the later, and the development of the later sciences has often given a new impetus to the further advance of the older. The increasing knowledge of the physical sciences has produced two great results: First, it has increased man's power over nature, and, secondly, it has done much to free the mind from the bonds of superstition. The conquest of nature has increased the food supply, as well as other forms of wealth, and therefore made possible a larger population and permitted the concentration of population in small areas. This increase of population, how-
