The seeming ineradicability of idealism then in this sense results from the fact that human beings are incapable of imagining anything other than this element of consciousness in which we are eternally submerged (even in sleep); incapable therefore of theorizing this phenomenon in the light of what it is not—by virtue of the law that identifies determination with negation (Spinoza). Such agnosticism is not a defense of idealism as a philosophy, but rather an acknowledgement of the limit under which it must necessarily place all philosophy.

—Fredric Jameson, Valences of the Dialectic, p. 7