Adam Smith
The division of labor, exchange, and self-interest can expand a nation's wealth, reflected in its citizens' living standards rather than hoarded gold.
Dividing production into specialized, repetitive tasks drastically increases labor productivity and spurs technological innovation.
The natural human propensity to barter and trade helps individuals pursuing their own interest organize a highly efficient economy.
For Smith, a commodity's real exchange value is the labor it can purchase or command, rather than its money price. Its real cost is the toil and trouble of acquiring it; its market price tends toward a natural price covering wages, rent, and profit.