  Rosenzweig moved to Leipzig for the winter and summer semesters of 1913. There, while still conducting his research on Hegel, he studied mathematics and jurisprudence, and began what was to become a close friendship with a young lecturer in jurisprudence, Eugen Rosenstock. The two began to meet regularly to discuss philosophical and theological matters. At stake for Rosenzweig appear to have been questions closely linked to those he had contemplated during the Baden-Baden experiment and which remained on his mind as he investigated Hegel’s coming of age in Hegel und der Staat: how can our radical subjectivity or selfhood be reconciled with our grasp of the world? and how must the divine be conceived such that it be understood as grounding and unifying both selfhood and worldliness? The failure at Baden-Baden had led Rosenzweig to question his earlier historicist view that individual subjects might find their fulfillment as subjects in the world by joining together to form a zeitgeistig unity, worshipping in the Zeitgeist “the God revealing itself in the here and now.” But how else was the relationship between self and world to be grasped? This question appears to have been the source of some existential disquiet for Rosenzweig, and heading into the summer of 1913, he appears to have entertained certain Gnostic notions that one could only realize one’s selfhood, and ground that selfhood in a relation to the divine, through a denial of the world. But on July 7, 1913, Rosenzweig engaged in an all-night discussion with Rosenstock and his (Rosenzweig’s) cousin Rudolf Ehrenberg, which Rosenzweig would later look back on as the transformative event in his life. Over the course of this night, Rosenstock convinced Rosenzweig not only to rethink the significance of Christianity—Rosenzweig apparently came into that evening with a view of “true” Christianity as inherently anti-worldly, while Rosenstock stressed Christianity’s redemptive work in the world—but even that a Christian life grounded in revelation and devoted to the mission of redeeming the world through history represented the only coherent and compelling path to the kind of reconciliation of selfhood and worldliness which Rosenzweig sought. Rosenstock’s challenge precipitated a crisis in Rosenzweig: he later claimed to have spent the hours after the conversation alone in his room, pistol at hand, “face to face with the Nothing.” He emerged from the experience determined to convert to Christianity in order thereby to take up his place in the historical realization of redemption in the world.