In early philosophy each feature of social life is referred directly to human nature. The idea of auxiliary phenomenon or by-product is wanting. War is ascribed to the bad passions of men, and not to the pressure of population. Theological beliefs flow from religious intuitions. Worship arises from universal instincts. The ethical code is a deliverance of individual consciences. The actual form of the family is derived from the "natures" of men and women and children. The law objectifies the moral consciousness of mankind. In this vein Aristotle traces slavery to the natures of the born inferior and the born superior. Montesquieu makes despotism rest on fear, monarchy on honor, and a republic on virtue. Adam Smith traces the division of labor to a propensity "to truck, barter, or exchange one thing for another." Carlyle sees in dignities of rank a product of the hero-worship in human nature.
On the other hand, the more we delve beneath the surface, the more we discover sympathetic connections between things. The fuller our knowledge, the more impressed we are with the relativity of each class of social phenomena to other classes. Society no longer falls apart into neat segments like a peeled orange. State, law, religion, art, morals, industry, instead of presenting so many parallel streams of development, are studied rather as different aspects of one social evolution.
We see that standards of conduct are in intimate relation with beliefs, that laws are correlated with moral standards, that both reflect economic necessities, and that these, in turn, depend on the forwardness of the arts or on the relation of population to land. The state is explained, not out of human nature, but in connection with ethnic heterogeneity, militant activities, or economic inequalities. The development of religion is shown to follow step by step the development of relations within the social group. Thus a disturbance in one department of social life awakens echoes and reverberations clear around the circle. It is a perception of this truth which leads Ingram, the historian of political economy, to declare: "No rational theory of the economic organs and functions of society can be constructed if they are considered as isolated from the rest." "A separate
