We are vitally dependent on the earth’s biosphere, yet “the containers and atmospheres that we must allow to surround us can no longer be taken for granted.”25 We have entered an age in which our “surroundings themselves became, or were recognized as [becoming], constructs.”26 It is this realization that ushers in the Anthropocene. Foams is an anthropocenic book avant la lettre. Sloterdijk has diagnosed the Anthropocene as marking the irrevocable end of what he calls the “backdrop ontology,” the state in which nature is nothing other than “the inoperative scenery behind human operations.”26 The backdrop is now becoming the foreground, and rapidly becoming a matter of life and death. Immune systems have become central concerns. Making the immune systems explicit means, Sloterdijk writes, in the most important and tragic messages of the book, that human intelligence must break its ancestral habit of trusting to the “backdrop ontology,” what the American philosopher Wilfrid Sellars wistfully called the myth of the given.28