The real and effectual discipline which is exercised over a workman is that of his customers. It is the fear of losing their employment which restrains his frauds and corrects his negligence.
More Adam Smith quotes :
It is not from the benevolence of the butcher, the brewer, or the baker that we expect our dinner, but from their regard to their own interest.Adam Smith
The 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 Smith