John Maynard Keynes England, 1883-1946 His ideas on the causes of unemployment revolutionalized macroeconomic theory and profoundly altered government's involvement in the economy.

Karl Marx Germany, 1818-1883 Intellectual father of modern day Marxist economics, he predicted that capitalism would be ultimately destroyed by its own inherent

David Ricardo England, 1772-1823 His theory that landlords enriched themselves at the expense of society led him to campaign tirelessly in Parliament and in print for free trade.

Adam Smith Scotland, 1723-1791 The father of modern economics, he saw the market system acting as an "invisible hand" which leads people to unintentionally promote society's interests while pursuing their own.