Ludwik Fleck, the Polish philosopher of science, maintained that scientific discovery is influenced by social, political, historical, psychological, and personal factors. The determinants of Freud's Jewish identity are examined from this Fleckian perspective, as is the impact of that complex identity on his creation of psychoanalysis as a science. Three strands contributing to his Jewish identity are identified and explored: his commitment to the ideal of Bildung, the anti-Semitism of the times, and his “godlessness.” Finally, the question is addressed of what it means that psychoanalysis was founded by a Jew. For Freud, psychoanalysis was a kind of liberation philosophy, an attempt to break free of his ethnic and religious inheritance. Yet it represented at the same time his ineradicable relationship with that inheritance. It encapsulated both the ambivalence of his Jewish identity and the creativity of his efforts to resolve it.