Everything happens at the surface in a crystal which develops only on the edges. Undoubtedly, an organism is not developed in the same manner. An organism does not cease to contract in an interior space and to expand in an exterior space – to assimilate and to externalise. But membranes are no less important, for they carry potentials and regenerate polarites. They place internal and external spaces into contact, without regard to distance. The internal and external, depth and height, have biological value only through this topological surface of contact. Thus, even biologically, it is necessary to understand that “the deepest is the skin.”
– Gilles Deleuze, The Logic of Sense, p. 119
Between the two presents of Chronos – that of the subversion due to the bottom and that of the actualisation in forms – there is a third, there must be a third, pertaining to the Aion. In fact, the instant as the paradoxical element or quasi-cause which runs through the entire straight line must itself be represented. It is even in this sense that representation can envelop an expression on its edges, although the expression itself may be of another nature; and that the sage can “identify” with the quasi-cause, although the quasi-cause itself is missing from its own identity. The present of the Aion representing the instant is not at all like the vast and deep present of Chronos: it is the present without thickness, the present of the actor, dancer, or mime – the pure perverse “moment.” It is the present of the pure operation, not of the incorporation. It is not the present of subversion or actualisation, but that of the counter-actualisation, which keeps the former from overturning the latter, and the latter from being confused with the former, and which comes to duplicate the lining (redoubler la doublure).
– Ibid., pp. 191-192