This is Adam Smith speaking – literally speaking, because the words come from the transcript of his “Lectures on Jurisprudence.” Smith is discussing the “principle in the human mind” on which is based the famous disposition to “truck, barter, and exchange,” the cornerstone on which the equally famous division of labor is based. For the division of labor could not take place unless people wanted to exchange their wares. Evidently, to Smith this exchange did not take place because of the direct appeal of self-interest. It required an exercise of persuasion to convince the buyer that he would be better off exchanging whatever he had for what the seller offered. “The offering of a shilling, which to us appears to have so plain and simple a meaning,” says Smith, “is in reality offering an argument to persuade one to do so and so for it is in his interest.”

Thus, in the opinion of the first, and to many still the greatest, economist, the basis for economic relationships lies not in a disinterested calculation of advantages, but in the “faculties of reason and speech” that underlie the capacity for persuasion. Rhetoric – the art of speaking – is the rock on which the mighty edifice of economics stands.