The Thing § 177

When we say mortals, we are then thinking of the other three along with them by way of the simple oneness of the four.

Earth and sky, divinities and mortals—being at one with one another of their own accord—belong together by way of the simpleness of the united fourfold. Each of the four mirrors in its own way the presence of the others. Each therewith reflects itself in its own way into its own, within the simpleness of the four. This mirroring does not portray a likeness. The mirroring, lightening each of the four, appropriates their own presenting into simple belonging to one another. Mirroring in this appropriating-lightening way, each of the four plays to each of the others. The appropriative mirroring sets each of the four free into its own, but it binds these free ones into the simplicity of their essential being toward one another.

The mirroring that binds into freedom is the play that betroths each of the four to each through the enfolding clasp of their mutual appropriation. None of the four insists on its own separate particularity. Rather, each is expropriated, within their mutual appropriation, into its own being. This expropriative appropriating is the mirror-play of the fourfold. Out of the fourfold, the simple onefold of the four is ventured.

This appropriating mirror-play of the simple onefold of earth and sky, divinities and mortals, we call the world. The world presences by worlding. That means: the world's worlding cannot be explained by anything else nor can it be fathomed through anything else. This impossibility does not lie in the inability of our human thinking to explain and fathom in this way. Rather, the inexplicable and unfathomable character of the world's worlding lies in this, that causes and grounds remain unsuitable for the world's worlding. As soon as human cognition here calls for an explanation, it fails to transcend the world's nature, and fells short of it. The human will to explain just does not reach to the simpleness of the simple onefold of worlding. The united four are already strangled in their essential nature when we think of them only as separate realities, which are to be grounded in and explained by one another.

Martin Heidegger (GA 7) The Thing - Poetry, Language, Thought