be interpreted by being traced back to passages from Hoelderlin's poetry.

In the last stanza of his hymn "The Ister River," Hoelderlin says:

"It is useful for the rock to have shafts,
And for the earth, furrows,
It would be without welcome, without stay."

There is no welcome where no meal, no food and drink can be offered. There is no stay here for mortals, in the sense of dwelling at home. If mortals are to be made welcome and to stay, there must be water from the rock, wheat from the field:

"It is useful for the rock to have shafts,
And for the earth, furrows."

Shafts pierce the rock. They break a path for the waters. The Greek word for pierce is κεντεῖν; κέντρον is the spike. The centaurs owe their nature to the piercing spear. This piercing and path-breaking is part of "what gives life." Hoelderlin, too, sees it in this light, as one of his enigmatic translations of Pindar fragments (Hell. V, 2, 272) clearly shows. There it says: "The idea of centaurs may well he the idea of the spirit of a stream, since the stream makes a path and a border, by force, on the earth that originally is pathless and gTOwing upward. Its image is therefore in the place of nature where the bank is rich in rocks and grottoes. . . . "

"It is useful for the rock to have shafts/ And for the earth, furrows." We should be listening altogether too superficially, and thinking too little, if we were to interpret the "it is useful" here to mean only "it is necessary ..." Shafts are no more necessary to the rock than furrows to the earth. But it belongs to the essence of welcome and being at home that it include the welling of water and the fruits of the field. "It is useful" says here: there is

Martin Heidegger (GA 8) What Is Called Thinking?