The learned ignore the evidence of their senses to preserve the coherence of the ideas of their imagination.
Adam SmithThe propensity to truck, barter and exchange one thing for another is common to all men, and to be found in no other race of animals.
Adam SmithThus the labour of a manufacture adds, generally, to the value of the materials which he works upon, that of his own maintenance, and of his masters profits. The labour of a menial servant, on the contrary, adds to the value of nothing.
Adam Smith