A patient, genealogical investigation of the dichotomies that are foundational to the Western philosophical tradition. We are so used to distinguishing between the possible and the real, between essence and existence that we do not realize that these distinctions, which seem so obvious to us, are the result of a long and laborious process that has led to the splitting of being--the "matter" of thought--into two fragments that are both conflicting and intimately intertwined. This book argues that the ontological-political machine of the West is based on the splitting of this "matter," without which neither science nor politics would be possible. Without the partition of reality into essence and existence and into possibility and actuality, neither scientific knowledge nor the ability to control human action--which characterizes the historical power of the West--would have been possible. If we could not suspend the exclusive concentration of our attention on what immediately exists (as animals seem to do), to think and define its essence, Western science and technology would not have experienced the advances that characterize them. And if the dimension of possibility disappeared entirely, neither plans nor projects would be thinkable, and human actions could be neither directed nor controlled. The incomparable power of the West has one of its essential presuppositions in this ontological machine.