Adam Smith was an 18th century Scottish philosopher who is considered the father of modern economics. He wrote two influential works, The Theory of Moral Sentiments and An Inquiry into the Nature and Causes of the Wealth of Nations. Smith introduced three key economic concepts: division of labor which improves productivity by having workers specialize in separate tasks, the invisible hand whereby individual self-interest and competition indirectly promote the greater good, and that a nation's wealth is defined by the total goods and services produced rather than monetary wealth.