Peter Sloterdijk first presented the following text as his inaugural lecture for the Chaire Emmanuel Levinas, March 4, 2005 at the University of Strasbourg. To a certain extent, it bears homage to that great thinker of the complex Other. However, other than taking a political stance, Sloterdijk prefers the perspective of a curator who is concerned about conserving the past century’s critical impulse, which today’s consumerism and the collapse of Left-wing traditions tend to render ghostly. In the first two parts of his essay, Sloterdijk argues that if in contemporary diagnoses the twentieth century appears as a time of confusions, this is because it is an “Age of Extremes” (Eric Hobsbawm): an age of revolts against complexities by the critical reference of all actual or objective states of affairs to a basic cause or fundamental factor. The subject of this extremist reason is defined by its vassalage, apostolate, and mediality in relation to a commanding and disinhibiting reality. Its forerunners are champions of “good crime” such as Marquis de Sade and the young Hegelians; its exemplary twentieth-century cases are Lenin and Mao. Alain Badiou is right to note that the memory of their critical projects is rapidly giving way to the uncontested status of today’s global neoliberalist ideology. Yet, Sloterdijk argues, this is not necessarily a bad thing, not even for critical thought. In the third and fourth parts of his essay, his explicit aim is to “translate” Badiou’s thesis that the twentieth century was marked by a “passion for the real” into the context of his own project of spherology. The twentieth century consists primarily of the activation of the real in a passion for technological and economic antigravitation. The result is the slow but unavoidable emancipation of Western civilization from “the dogmatic opportunism of the real as power-of-the-base-from-below” toward “a free-moving position intermediate between the heavy and antigravitational tendencies.” Economically, the ending of scarcity (Entknappung) and, technologically, the exoneration (Entlastung) of the burdens of human life by the intrusion of new motive forces into human propulsive arrangements have led to the death throes (“Agonie”) of the belief in the base/superstructure division and the radicalism or fundamentalism derived from it. If the twentieth century can still inspire us today, this is because its reprogramming of the pitch of existence (Daseinsstimmung) paves the way for a “critique of extremist reason,” a “post-Marxist theory of enrichment,” a “new interpretation of dreams,” and a “general economy” of energy resources based on excess and dissipation.