  If the essence of human Being is to dwell in the fourfold, then human beings are to the extent that they so dwell. And this will be achieved to the extent that human beings realize the “basic character of dwelling”, which Heidegger now argues is a matter of safeguarding “the fourfold in its essential unfolding” (Building Dwelling Thinking, 352). Such safeguarding is unpacked as a way of Being in which human beings save the earth, receive the sky as sky, await the divinities as divinities, and initiate their own essential being as mortals. Perhaps the best way to understand this four-way demand is to explore Heidegger's claim that modern humans, especially modern Western humans, systematically fail to meet it. That is, we are marked out by our loss of dwelling—our failure to safeguard the fourfold in its essential unfolding. This existential malaise is what Heidegger refers to in the Letter on Humanism as the oblivion of Being. As we are about to see, the fact that this is the basic character of our modern human society is, according to Heidegger, explained by the predominance of a mode of sense-making that, in the Contributions, he calls machination, but which he later (and more famously) calls technology. 