Since the end of German idealism and the Hegelian definition of the "need for philosophy", the auto-reflection of philosophy has changed. This is attested to by the modification of writing since Kierkegaard and Nietzsche. The elaboration of language itself is required by the elaboration of a thinking which takes the form of a regressive meditation (Rückbesinnung) that is not only historical and critical. It is below the level of objective knowledge and lived experience that always more radical questions are asked. This paper treats this subject with reference to the Heideggerian "phenomenology of the inapparent". What sets in motion the manifold thinking of the Simple? What speaks in the "Es gibt"? What is responding and corresponding? In Levinas' writings the progression towards the limits of descriptive phenomenology goes together with a meditation on philosophical thinking as a questioning which rises again behind the given replies.