The fourfold, unnamed in "The Origin of the Work of Art". Françoise Dastur explains:

We have therefore to think together, as a whole, the holy dimension of the world, the opening of the world as the setting forth of the earth and the world as the locus of the historicality of a collective singular being. We could then consider that this conception of world in the middle of the thirties is midway between the human Umwelt from 1927 and the world considered as the Geviert [Fourfold] in the fifties. Heidegger says explicitly in The Thing that the fourfold--earth and sky, divinities and mortals--is the worlding of the world.*

* All the dimensions of the fourfold are already present in 1935 except the sky. But we can perhaps consider that what is called in 1935 "earth" and which is understood as "the whole" (das Ganze) and linked to the Greek Physis, i.e., to the emerging and coming into light of everything, posseses a lighted side which later will be called sky. On the same page [Freiburg Version of "The Origin of the Work of Art"], Heidegger underlines that physis has the same root as the word phaos, phos, meaning light.

P. 131

I expect Heidegger wrote φάος, φῶς. This indicates that in 1935, he had not yet turned from “The Lighting” to “The Clearing”.  ¶ 10:30 PM