  Another line of twentieth-century interpretation also focused on the isolation of the subject in the Second Meditation. In the course of that Meditation, Descartes accepts that he knows the contents of his mind, including putative sensory experiences, even though he doubts the existence of his body. Some philosophers have concluded from this that Descartes believed that human beings actually can, in their natural state, have sensory experiences even if they lack a body. But Descartes in fact denied that possibility. In his metaphysics, sense perception and imagination depend for their existence on mind–body union. There can be intellectual perceptions that do not depend on the brain. But acts of imagination and sense perception require the brain (Pass. I.19–20, 43). Thus, Descartes did not in fact hold that we might have all of our sense experiences even if we had no brain. Rather, he allowed that he could conceive his sensory experiences independent of the brain, and that, if God were not supremely good, God could produce those experiences in us independent of the brain; but because God's perfection is inconsistent with deceit, he would never do this. Hence, conceivability does not in all cases—and especially not in cases of mere ignorance, as in the Second Meditation—yield metaphysical possibility (as we have seen in the Discourse argument for the mind–body distinction).