Eileen Markley (1886–1976). They had one daughter, sociologist Helena Znaniecki Lopata, born 1925. Importance Polish sociologist and historian of ideas Jerzy Szacki writes that Znaniecki's major contributions include: the founding of sociology in Poland; his work in empirical sociology; and his work in sociological theory. Szacki notes that Znaniecki sought to bridge a number of gaps: between empirical sociology and more theoretical approaches; between objectivity and subjectivity; between humanistic and naturalistic methodologies and viewpoints; and between American and European intellectual traditions. Szacki writes that, while Znaniecki's theoretical contributions were subsequently pushed into the background by Talcott Parsons' "functionalism", Znaniecki offered the most ambitious sociological theory known to America before Parsons. Znaniecki's most famous work remains The Polish Peasant in Europe and America (1918–1920), co-authored with William I. Thomas. His other major works include Wstęp do socjologii (An Introduction to Sociology, 1922), The Method of Sociology (1934), Social Actions (1936), The Social Role of the Man of Knowledge (1940) and Cultural Sciences (1952). Themes Empirical sociology Znaniecki's contributions to empirical sociology began after, and were influenced by, his collaboration with William I. Thomas. The Polish Peasant in Europe and America (1918–1920), a five-volume work which he wrote with Thomas, is considered a classic of empirical sociology. It is a study of Polish immigrants to America, based on personal documents. The work became a landmark study of Americanization — of how new immigrants to the United States "become Americans". This work represents Znaniecki's most valued contribution to empirical sociology. Most of his other works focused on theory, the only other notable exception being Miasto w świadomości jego obywateli (The City in the Consciousness of its Citizens, 1931). Sociology: theory and definition A key element of Znaniecki's sociological theory is his view of sociology in particular, and of the social sciences in general, as a scientific field uniquely different from the natural sciences. Znaniecki defines sociology as a study of social actions. His recommended methodology was analytic induction: analysis of typical case studies, and generalization from them. Znaniecki's theories form a major part of sociology's action theory, and his work is a major part of the foundation of humanistic sociology. Another term connected with Znaniecki's theories is "systematic sociology" ("socjologia systematyczna"). He sought to create a grand sociological theory, one that would bridge the gap between empirical sociology and more theoretical approaches. Znaniecki criticized the widespread definition of sociology as the study of