Surplus and Profit

In Smith's Propensity to Barter, the possession of a surplus is entailed as a means to an exchange for a fulfillment of a some deficiency. Now, a profit is a species of Surplus, and, hence, has value as a means to the fulfillment of some deficiency. But, the identification of Self-Interest and Profit treats the latter as an end. Thus, the concept, pervasive in Capitalism, of Barter and Exchange as means to Profit not merely supervenes on Smith's original premises, but inverts, and, perhaps, perverts, them.