In his "Building Dwelling Thinking" (in: "Poetry, Language, Thought") Martin Heidegger relates to his key concept of "fourfold" as a central aspect of dwelling (see previous part of the summary). The four elements of the fourfold are earth and sky, divinities and mortals. The fourfold is a kind of fullness which is a part of dwelling. This unity of the fourfold cannot be divided into its components and each one of these can only be what it is only when the others are kept in mind. Therefore, Heidegger claims, a man is not only a being in the world, but a part of the fourfold of earth, sky, divinities and mortals.
Earth is the supporting ground on which we stride. It supports us in the most physical sense and also by nurturing, watering and providing for us. Despite its perceived stability, the earth as part of the fourfold is an elusive element.
The sky as part of Heidegger's fourfold as the sky in their usual referential meaning but they have some additional layers of meaning. Human beings' gaze towards the sky gives birth the metaphors that reflect the fact that we are always both here but also "beyond". Therefore "sky" as a part of the fourfold are a spiritual component relating to eternity.
The mortals in Heidegger's fourfold are human beings. Relating to mankind as mortals emphasizes our finiteness and instability of our existence. Only through "memto mori", the remembering of our inevitable death, can we come to terms with our essential nature. By this we can sustain a proper dwelling which leads, according to Heidegger, to a "good death" as human beings which in not nothingness but rather our essential nature.
Following Holderlin, Heidegger understands the divinities as the most basic criterion of mankind. God for Heidegger is a poetic fiction, an anonymous creator and provider. And it is through his anonymity that god sets the standards for dwelling in the world, by his concealed presence in everything that surrounds us.
Heidegger's fourfold is the unity of earth, sky, mortals and divinities. It is part of our being in space and the site in which dwelling takes place. Human beings provide access to the fourfold by being a part of it and by their dwelling, sustaining the fourfold and its unity.
In this fourfold unity humans exist in their dwelling which is "done right" by "sparing the earth" and maintaining its true nature without exploiting it. Dwelling according the Heidegger is accepting the sky as sky, with their blessing and atrocities. Dwelling is also constituted by "awaiting the divinities as divinities" and by recognizing our limited existence.