In Christian Morgenstern’s poem Die unmögliche Tatsache, the impossible fact, Palmström reasons his way out of something that happened to him. The poem ends: Und er kommt zu dem Ergebnis: / Nur ein Traum war das Erlebnis. / Weil, so schließt er messerscharf, / nicht sein kann, was nicht sein darf. He comes to the result that the experience was only a dream, because, as he concludes with razor-sharp logic, what must not be cannot be. The poem appeared in the collection Palmström in 1910. Its last lines became a common saying.