senior American economists agreed with Keynes through most of the 1930s. Yet his ideas were soon to achieve widespread acceptance, with eminent American professors such as Alvin Hansen agreeing with the General Theory before the outbreak of World War II. Keynes himself had only limited participation in the theoretical debates that followed the publication of the General Theory as he suffered a heart attack in 1937, requiring him to take long periods of rest. Among others, Hyman Minsky and Post-Keynesian economists have argued that as result, Keynes's ideas were diluted by those keen to compromise with classical economists or to render his concepts with mathematical models like the IS–LM model (which, they argue, distort Keynes's ideas). Keynes began to recover in 1939, but for the rest of his life his professional energies were directed largely towards the practical side of economics: the problems of ensuring optimum allocation of resources for the war efforts, post-war negotiations with America, and the new international financial order that was presented at the Bretton Woods Conference. In the General Theory and later, Keynes responded to the socialists who argued, especially during the Great Depression of the 1930s, that capitalism caused war. He argued that if capitalism were managed domestically and internationally (with coordinated international Keynesian policies, an international monetary system that did not pit the interests of countries against one another, and a high degree of freedom of trade), then this system of managed capitalism could promote peace rather than conflict between countries. His plans during World War II for post-war international economic institutions and policies (which contributed to the creation at Bretton Woods of the International Monetary Fund and the World Bank, and later to the creation of the General Agreement on Tariffs and Trade and eventually the World Trade Organization) were aimed to give effect to this vision. Although Keynes has been widely criticisedespecially by members of the Chicago school of economicsfor advocating irresponsible government spending financed by borrowing, in fact he was a firm believer in balanced budgets and regarded the proposals for programs of public works during the Great Depression as an exceptional measure to meet the needs of exceptional circumstances. Second World War During the Second World War, Keynes argued in How to Pay for the War, published in 1940, that the war effort should be largely financed by higher taxation and especially by compulsory saving (essentially workers lending money