Possibility (to be able to be) and contingency (to be able not to be) are the operators of subjectification, the point in which something possible passes into existence, giving itself through a relation to an impossibility. Impossibility, as negation of possibility (not [to be able]), and necessity, as negation of contingency (not [to be able not to be]) are the operators of desubjectification, of the destruction and destitution of the subject - that is, processes that, in subjectivity, divide potentiality and impotentiality, the possible and the impossible. The first two constitute Being in its subjectivity, that is, in the final analysis as a world that is always my world, since it is in my world that impossibility exists and touches (contingit) the real. Necessity and possibility, instead, define Being in its wholeness and solidity, pure substantiality without subject - that is, at the limit, a world that is never my world since possibility does not exist in it. Yet modal categories, as operators of Being, never stand before the subject as something he can choose or reject; and they do not confront him as a task that he can decide to assume or not to assume in a privileged moment. The subject, rather, is a field of forces always already traversed by the incandescent and historically determined currents of potentiality and impotentiality, of being able not to be and not being able not to be.
- Giorgio Agamben, Remnants of Auschwitz, pp. 147-148 (via spiritandteeth)