Introductory: We have already noted the fact that the form of industrial society in which we live, and which we call capitalism, is characterized by the production and exchange of commodities or wares, salable goods. The sole motive of capitalist enterprise is the sale of goods at a profit. So long as the capitalist can obtain a satisfactory profit he does not care--except in rare instances, which need not be considered--what kind of commodities he deals in. If a greater profit can be obtained from the manufacture and sale of shoddy clothing than from the manufacture and sale of good clothing he will, so far as he is free to do so, concern himself with the former. This is too obvious a fact to require demonstration. It is one of the commonplace expressions of every-day life that men are in business "for the profit there is in it." This is not a moral criticism of capitalist society, but a simple recognition of one of its essential and characteristic features.
The objective of capitalist production being the realization of profit, it follows that if our analysis of capitalist society is comprehensive and helpful we must learn a good deal about profit, its nature, its origin and its function in the social organism. Marx's theory of surplus-value is explanation of these phenomena.
Exchange of equal values: In our discussion of value and its price-form we saw that the exchange of commodities takes place through the medium of money, itself a commodity. We are now to consider the process of exchange itself. That somehow or other profits are realized through the exchange of commodities is evident, but that does not mean that the proportion of the total of existent values which we call profit is created by exchange. On the contrary, it is very easily seen that it is not. If two men, A and B, exchange