Following a short review of Freud's concepts of humor and the joke, the author concentrates on the specific nature of the Jewish joke as a spiritual genre of East European Jewry. The problem of East European Jewry's split identity is analyzed, in the light of the history of its emancipation and of the Haskalah—the Jewish Enlightenment—over the last two centuries. This split is reflected by the incongruous dissociation between traditional talmudic, analytical thinking and emotional-conceptual thinking. The joke expresses this incongruity by the means of concretism, whose implicit reductio ad absurdum elicits a comical effect. Concretism, characterized by Freud as “faulty reasoning,” is a characteristic of jokes, and particularly of Jewish jokes. It also characterizes the child's thinking and thinking disturbances found in psychoses and psychosomatic illness. The identity aspect inherent in the concretism of Jewish jokes, with their evocation of guilt feelings, their relativizing and integrative quality, is illustrated by a number of examples.