Schelling calls it the boundary that sustains the dual extensity between excitability and irritability, remisniscent of Plato’s chora. It’s the proverbial indivisible remainder that splits our consciousness of reality between quantitative indifference and mere difference, between potency and the immanence of phenomenology. It is the space interval where consciousness can posit the self-evidence of negativity (lacking in Spinoza).
But we owe it to Spinoza that we have a conception of nature that can evolve infinitely without an inhibited point of activity, call it absolute necessity, regardless if at some remote point in the ancestral past, the abyssal point of an event, nature’s infinity found a tentative finite arrest, an arrested stream of causes and effects that we now call freedom.
Freedom just happened without the need to explain it as a miracle, not even as a contingency, much less, in terms of experience which has never known such organization of nature. This is how the pure demonstration of necessity, that is, in terms of mathematics or geometry, where there ought to be no movement in time (the movement as the point-attractor of contingency where miracles are either phenomenologically or computationally contested), becomes problematic. But is this what Plato already means in the Timaeus: the discovery of the maker of the universe cannot be explained to anyone?
Spinoza’s Ethics is therefore a repeat axiomatization of the non-evidence of freedom by demonstrating the standpoint of absolute necessity (which is the standpoint of geometry or mathematics). There is no contradiction in that. A geometrician knows how to draw x and y grids, proof that he acts in space, that there is movement in pure necessity, that freedom is an arrested infinity. It is already dead as inhibited infinite, hence, the non-evidence.