Heidegger speaks of the lines of the hymn concerning the invitation to Hercules. We can know nothing of the Ister or the hymn if we do not understand who this guest is. The appropriation of one's own "is" only as the encounter and guest-like dialogue with the foreign. The river must remain in the realm of its source in such a way that it flows toward it from out of the foreign, which is why it "appears, however, almost / To go backwards." Heidegger again uses the word "Wirbeln" to indicate this swirling near the source.