Kalecki has been called "one of the most distinguished economists of the 20th century" and "likely the most original one". It is often claimed that he developed many of the same ideas as John Maynard Keynes before Keynes, but he remains much less known to the English-speaking world. He offered a synthesis that integrated Marxist class analysis and the new literature on oligopoly theory, and his work had a significant influence on both the neo-Marxian ("Monopoly Capital") and post-Keynesian schools of economic thought. He was one of the first macroeconomists to apply mathematical models and statistical data to economic questions. Being also a political economist and a person of leftist convictions, Kalecki emphasized the social aspects and consequences of economic policies.