Fackenheim eventually became dissatisfied with the modern existential conception of revelation elaborated by Rosenzweig and Buber. This should not be confused with his ever-mounting concern with the Holocaust, although both emerged in tandem. Fackenheim articulated Rosenzweig’s and Buber’s basic conception better than they did, as the ever-present possibility of revelation, with a content reduced to nothing but pure Presence. This rested on the prior philosophic argument that the possibility of revelation cannot be refuted, an argument that remains valid despite modern rationalistic criticism. Fackenheim learned this from Leo Strauss, who thought through the Buber–Rosenzweig position better than they had themselves. This initiated a fruitful period of original theological reflection for Fackenheim, between 1945 and 1967, but he found this concept was insufficiently coherent to be implemented as a workable guide to actual religious faith and life.