Keynes’s masterpiece, The General Theory of Employment, Interest and Money, argued that government intervention and fiscal policy are necessary to manage economic cycles and prevent depressions. His work provided the intellectual foundation for the post-war welfare state and the Bretton Woods system. A member of the Bloomsbury Group, he was also a patron of the arts and a key figure in British intellectual life. His emphasis on the importance of aggregate demand and state spending remains a central, though often debated, pillar of modern economic policy.