  It is worth pausing here to comment on the fact that, in his 1935 essay The Origin of the Work of Art, Heidegger writes of a conflict between earth and world. This idea may seem to sit unhappily alongside the simple oneness of the four. The essay in question is notoriously difficult, but the notion of the mystery may help. Perhaps the pivotal thought is as follows: Natural materials (the earth), as used in artworks, enter into intelligibility by establishing certain culturally codified meanings—a world in the sense of Being and Time. Simultaneously, however, those natural materials suggest the existence of a vast range of other possible, but to us unintelligible, meanings, by virtue of the fact that they could have been used to realize those alternative meanings. The conflict, then, turns on the way in which, in the midst of a world, the earth suggests the presence of the mystery. This is one way to hear passages such as the following: “The world, in resting upon the earth, strives to surmount it. As self-opening it cannot endure anything closed. The earth, however, as sheltering and concealing, tends always to draw the world into itself and keep it there” (Origin of the Work of Art 174).