William Graham Sumner (1840-1910) was an American academic and professor at Yale College. For many years he had a reputation as one of the most influential teachers there. He was a polymath with numerous books and essays on American history, economic history, political theory, sociology, and anthropology. His popular essays gave him a wide audience for his laissez-faire advocacy of free markets, anti-imperialism, and the gold standard. He was a president of American Sociological Association from 1908 to 1909. As a sociologist, his major accomplishments were developing the concepts of diffusion, folkways, and ethnocentrism. He heavily criticized socialism/communism. His works include: What Social Classes Owe to Each Other (1883), Protectionism (1885), Folkways (1907) and The Forgotten Man (1919).