In this paper the author points to a puzzle raised by Freud's contradictory use of an analogy of a jigsaw puzzle. She shows how, through the attempt to resolve this puzzle, meanings and implications of Freud's difficult struggle with his search for truth in Moses and monotheism come alive, both in Freud's writing and in the author herself. Central to this struggle is an encounter with the sources of doubt and conviction that ultimately allows one to embrace ideas experienced as true, although they are not demonstrable evidentially The paper sheds light on the importance of Moses and monotheism as a theoretical text that reflects on developments in Freud's thinking on truth, and the possibility dangers and inherent difficulties of grasping it.