Paul Celan, one of the greatest German language poets of the XXth century, is also one of its greatest translators. In the five-volume current edition of his Complete Works (Suhrkamp) two volumes contain his translations, mostly of poetry, from seven languages and of about fifty authors. This article attempts to show that the same poetics underlies both the act of writing and that of translating, and that this double production was Celan's answer to an ethical challenge : to recreate a human language, open to alterity, in the shadow of the specific historicity of living after Auschwitz.