Florian Witold Znaniecki was a Polish sociologist born in 1882 in Russian Empire. He moved to the US in 1914 and returned to Poland in 1920, but had to leave again in 1939 due to World War 2, settling at the University of Illinois. He is known for his work on analytic induction and defining personality types. His 1918 book "The Polish Peasant in Europe and America" is considered foundational to modern empirical sociology.