Among the many mysteries surrounding “the fourfold” is the almost total absence of any attempt by Heidegger scholars to explain what it is. Usually the topic doesn't even make it to the index, and even when it does, it does so only in virtue of statements like “this conception [of the fourfold] is developed in a way one can only call mythic, and its philosophical import is therefore far from clear,” which is not really very helpful. Baffled by Heidegger's poetic brevity, commentators have consigned it to the silence of the too-hard basket.

Yet without understanding the fourfold - the fourfold of earth, sky, gods, and mortals - one can understand almost nothing of later Heidegger. Heidegger says that “dwelling,” as he calls it, is the human “essence” (QCT 28, P 257, PLT 213 ff.). But to dwell is to “belong within the fourfold of sky and earth, mortals and divinities” (QCT 49; compare PLT 149). He also says that the fourfold is what “we call the world” (PLT 179). Without understanding the fourfold, therefore, one can understand neither later Heidegger's conception of the human being nor his conception of “world.”