Heidegger’s fourfold consists of earth, sky, gods, and mortals.
Heidegger understood the ‘earth’ as the ‘matter of existence,’ but not matter as conventionally understood as material, corporeal or concrete. The earth is the matter of existence in the sense that it designates a ‘non-quantifiable sensuous’ condition of experience grounded in phenomena, and not in the transcendent basis of experience. As Andrew J. Mitchell argues in his annotation of this aspect of Heidegger’s late philosophy, the earth requires no ground of experiencing, no permanent basis. In this sense, Heidegger does not consider even nature as a permanent ground of knowledge and experience, but instead as an ‘abyss’ (See Andrew J. Mitchell, The Fourfold: Reading the Late Heidegger, p. 81). (Remarkable here is Schelling’s influence on Heidegger, apropos of the notion of the ‘abyss of the past’). The earth, which is generally composed of stones, waters, plants, and animals, is the place that bears the groundless experience of existence, which gives us a sense of the world itself. In other words, the world develops a sense beyond the individuated character of the fourfold. Its sense is ‘distributed’, i.e., the phenomenal attribution of beings’ attunement to things, including Dasein, beyond’ each of the fourfold (ibid., p. 116), which generally ‘names the gathering of earth, sky, mortals and divinities’ (ibid., p. 3). Accordingly, this form of sense-giving ‘matters’ to Dasein, the being-in-the-world in the sense that it is a world understood by a being for which Being is an issue. This world does not precede Dasein, but is co-constitutive of sense-making. However, sense-making involves other parts of the fourfold – sky, gods, and mortals(ibid).
Suppose the earth provides a groundless ground of being in the world, restricting sense-making to the phenomenal. In this regard, the sky makes the distribution of phenomenal attunement and relationality of beings possible. The sky is the ‘domain of motion’ concerning the earth’s ungroundedness, whereby the earth acquires a phenomenal and temporal appearance. As Heidegger describes the sky in Poetry, Language, Thought –
The sky is the vaulting path of the sun, the shape-shifting course of the moon, the wandering gleam of the stars, the seasons of the year and their changes, the light and twilight of day, the dark and bright of the night, the clemency and inclemency of the weather, drifting clouds and blue depths of the aether. (p. 147).
Dasein or being-in-the-world is situated between the earth and sky. As being for which Being is a fundamental issue, Dasein is the ‘between and middle of beings themselves,’ itself an active being that founds a space of interaction, encounters and responses. Thus, it is in between the sky and the earth that encounters, relationalities, responses, ‘reciprocal communication and mutual contact,’ and time-reckoning are forged. But here comes an even more difficult challenge – how can things or beings be understood, which refers to their basic referentiality and denotation? Here, the divinities are called forth.
Recall that in his last interview, Heidegger says that ‘only a god can save us.’ But god would only reveal itself as a hint, unlike technology, which has replaced the old divinities, reducing everything to their calculable measures, their instrumental values. As a hint, God’s saving power (henceforth, we will refer to it as ‘godhood’, as Heidegger himself described) is both an obscure revelation of presence and absence. The gods of mythology, or the gods that poetry invoke, for instance, hint of this ‘godhood,’ of the promise of redemption. With the dominance of technology that replaced the pre-modern god, Heidegger designates this hint as the hint of the last god. As Mitchell says in analyzing this aspect of Heidegger’s later turn, ‘hints do not represent, they call’ (The Fourfold, p. 168). The underlying ethical provision of this hinting is quite apparent: where technology has replaced all measurements of being, their referentiality and denotations, the hint of godhood calls to those who can perceive the fundamental meaning of the death of God, that is, to stay away. However, staying-away does not mean complete withdrawal from the time of modernity, but instead a refusal to take modernity as absolute submission to machination. According to Heidegger, even technology is a gift, a donation of being through time. One secretly appropriates technology only to forge an adequate relation to it, which is to prepare for a sort of readiness for what machination offers, negatively or positively. In today’s parlance, this calls for an ethical relationship to technology.
The last member of the fourfold is ‘the mortals,’ which is Heidegger’s later replacement of the ‘term Dasein’ as being-in-the-world. Heidegger’s purpose is to shift the emphasis on being or determining one’s life in the world, to mortality or death. Another apparent reason for this shift is to embrace a more democratic sense of being, from Dasein’s singularity to the plural determination of beings as mortals, which presuppose a community. Heidegger ultimately emphasized mortality in the fourfold, given the technological saturation of existence, which strikes at the heart of the difference between humans and animals. For Heidegger, the animal is bound to the world and is incapable of escaping it, in contrast to the human who is alone capable of death, that is to say, the ‘human dies and dies continually,’ which ironically relegates the human to ‘constant departure from the world’ (ibid., p 219). The animal’s difference is that it does not die; instead, it comes to an end. In this sense, the animal ultimately belongs to the world, which by the way the animal cannot represent through concepts. The human that continues to die strongly suggests that through representation, the human is capable of death beyond the world, unlike the animal. The human continues to die in proportion to its capability to transform the sensible intuition of the external world into an ‘invisible, non-sensible, internal possession’ (ibid.).
To conclude, imagine how Heidegger would have thought about the planned expedition to colonize Mars: humans dying in Mars, but will continue to die even beyond the red planet.