What distinguishes Steuart from his predecessors and followers is his keen differentiation between specifically social labor which is represented in exchange value, and concrete labor which produces use-values. Labor, he says, which through its alienation creates a universal equivalent, I call _industry_. Labor as industry he distinguishes not only from concrete labor, but from all other social forms of labor.[31] It is to him the capitalistic form of labor in contrast to its antique and mediaeval forms. He is especially interested in the difference between capitalistic and feudal labor, of which he had observed the latter in its decaying forms both in Scotland and on his extensive travels over the continent. Steuart knew, of course, very well that products took on the form of commodities and commodities, the form of money in precapitalistic epochs as well; but he proves conclusively that it is only in the capitalistic period of production that the commodity becomes the elementary and fundamental form of wealth, and alienation [of commodities], the ruling form of acquisition and that consequently labor creating exchange value is specifically capitalistic in its character.[32] After different forms of concrete labor, such as agriculture, manufacture, navigation, trade, etc., had each in turn been declared the true source of wealth, Adam Smith proclaimed labor in general, and namely in its general social form of _division of labor_, to be the only source of material wealth or use-values. While ignoring in connection with the latter the part played by nature, he is troubled by it when he comes to deal with purely social wealth i. e. exchange value. To be sure, Adam determines the value of a commodity by the labor-time contained in it, but relegates the actual application of the principle to pre-Adamic times. In other words, what seems to him true from the standpoint of simple commodity, ceases to be clear as soon as the higher and more complex forms of capital, wage-labor, rent, etc. take its place. This he expresses by saying, that the value of commodities used to be measured by labor-time in the paradise lost of bourgeois society, in which men dealt with each other not as capitalists, wage-workers, landlords, tenants, usurers, etc., but merely as plain producers of commodities which they exchanged. He constantly confuses the determination of the value of commodities by the labor-time contained in them with the determination of their value by the value of labor. He becomes confused in working out the details and fails to see the objective equalization of different kinds of labor which the social process forcibly carries out, mistaking it for the subjective equality of the labors of individuals.[33] The transition from concrete labor to labor creating exchange value, i. e. to labor in its fundamental capitalistic form he tries to derive from the _division of labor_. Yet, while it is true that private exchange implies the