 This assertion of the primacy of practice is not unique to Leibowitz, reaching back in modern Jewish philosophy to Moses Mendelssohn and resurrected in recent decades by scholars such as Menachem Kellner (2006) and Kenneth Seeskin (1990). Steven Schwarzschild memorably termed this “the Jewish twist” (Schwarzschild 1977, 139) that in his view Jewish thinkers had applied since time immemorial to the systems of thought with which they grappled. Leibowitz, however, gives this idea its most extreme formulation.