Wayne Froman on an affinity between Rosenzweig's and Heidegger's use of Ereignis
In the Beiträge zur Philosphie: vom Ereignis, Heidegger tells us that das Ereignis awakens or elicits the question concerning Being. (Section 34, for example.) In Rosenzweig’s discussion of the revelation of das Ereignis, he finds that while the root-word of creation was simply "thus," the root-word of revelation’s primordial negation is "not otherwise." "Not otherwise" elicits the question: "not otherwise than what?" The response to that question is, not otherwise than everything, or in other words, not otherwise than what is. What then is the sense of "otherwise" here? The question concerns what is otherwise than beings, but at the same time, cannot otherwise than beings because it is not in the sense that beings are. In other words, the question concerns Being, as Heidegger understands it.
From "Heidegger and Rosenzweig: Vom Ereignis