In the fourteenth century, the Black Death killed as much as two thirds of Europe''s population; in the fifteenth, the introduction of moveable-type printing rapidly expanded Europe''s supply of human capital; between 1850 and 1914, Russia''s population almost tripled; and in World War I, the British blockade starved some 800,000 Germans. Each of these, Shocking Contrasts argues, amounted to an unanticipated shock, positive or negative, to the supply of a crucial factor of production; and elicited one of four main responses: factor substitution; factor movement to a different sector or region; technological innovation; or political action, sometimes extending to coercion at home or conquest abroad. This book examines parsimonious models of factor returns, relative costs, and technological innovation. It offers a framework for understanding the role of supply shocks in major political conflicts and argues that its implications extend far beyond these specific cases to any period of human history.