A multitude of subordinate wheels depend on the great central wheel. For if the clock runs, it is owing to the harmony of its various parts, from which it follows that, on this harmony ceasing, the clock gets out of order. But, besides the principal spring, there are others which, acting on or in combination with it, give to each clock a special character and a peculiar movement. Such, in the first place, is climate, that is to say, the degree of heat or cold, humidity or dryness, with its infinite effects on man's physical and moral attributes, followed by its influence on political, civil and domestic servitude or freedom. Likewise the soil, according to its fertility, its position and its extent. Likewise the physical régime, according as a people is composed of hunters, shepherds or agriculturists. Likewise the fecundity of the race, and the consequent slow or rapid increase of population, and also the excess in number, now of males and now of females. And finally, likewise, are national character and religion.--All these causes, each added to the other, or each limited by the other, contribute together to form a total result, namely society. Simple or complex, stable or unstable, barbarous or civilized, this society contains within itself its explanations of its being. Strange as a social structure may be, it can be explained; also its institutions, however contradictory. Neither prosperity, nor decline, nor despotism, nor freedom, is the result of a throw of the dice, of luck or an unexpected turn of events caused by rash men. They are conditions we must live with. In any event, it is useful to understand them, either to improve our situation or bear it patiently, sometimes to carry out appropriate reforms, sometimes to renounce impracticable reforms, now to assume the authority necessary for success, and now the prudence making us abstain. IV. The New Psychology. The transformation of psychology.--Condillac.--The theory of sensation and of signs.