If, however, we understand "Phenomenology" as the [process of] allowing the most proper concern of thought to show itself, then the title should read "Through Phenomenology to the Thinking of Being."6 This possessive [of Being], then, says that Being as such (Beon) shows itself simultaneously as that which is to-be-thought and as that which has want of a thought corresponding to it.7
This indication already brings me to touch upon your second question. It reads: "Granted that a 'reversal' has come-to-pass in your thinking, how has it come-to-pass? In other words, how are [we] to think this coming-to-pass itself?"
Your question admits of an answer only if first we make clear what "reversal" means, [or] more precisely, if one is ready to think through in becoming fashion what has already been said, instead of constantly circulating unwarranted assertions. The first time in my published writings that I spoke of the "reversal" was in the "Letter on Humanism" (1947, p. 71; separate edition, p. 17). The inference has thus been drawn that since 1947 Heidegger's thought has undergone "in-version," or even, since 1945, "con-version." No allowance whatever is made for reflection on the fact that a good number of years are needed before the thinking through of so decisive a matter can find its way into the clear. Perhaps the text cited below will serve to show that the matter thought in the term "reversal" was already at work in my thinking ten years prior to 1947. The thinking of the reversal is a change in my thought. But this change is not a consequence of altering the standpoint, much less of abandoning the fundamental issue, of Being and Time. The thinking of the reversal results from the fact that I stayed with the matter-for-thought [of] "Being and Time," sc. by inquiring into that perspective which already in Being and Time (p. 39) was designated as "Time and Being."
6 [Translator's note. The original title of this book was From Phenomenology to Thought, which, when translated into German, became Der Weg von der Phänomenologie zum Seinsdenken. What the writer understood by "Phenomenology" in this case must be gathered from the entire study that follows (but see especially below, pp. 624, 631). Be this as it may, Professor Heidegger's suggestion is a valuable one, and in view of it the title was changed to its present form just as the book went to press.]
7 [Translator's note. For the sense of Seyn and its translation by "Beon," see below, pp. 457, 554. Braucht in the present context might be translated by "needs," but we prefer "has want of" for reasons that appear below, pp. 597, 600, 614.]