In 1776, Scottish philosopher Adam Smith published 'An Inquiry into the Nature and Causes of the Wealth of Nations.' This foundational text of modern economics introduced the concept of the 'invisible hand'—the idea that individuals pursuing their own self-interest in a free market inadvertently promote the good of society as a whole. Smith argued against 'mercantilism' (government-controlled trade) and in favor of free trade, the division of labor, and competition. His work provided the intellectual justification for capitalism and the industrial growth of the 19th century. Smith's theories emphasized that a nation's wealth should be measured not by its gold reserves, but by its per capita income and productivity, changing how governments approached trade and domestic policy.