If sensations were produced by some activity in the mind, the thinker would be aware of that activity at the time of its operation.

Interestingly, Descartes would agree that experiential resources cannot solve the problem. By the Sixth Meditation, however, Descartes purports to have the innate resources he needs to solve it – notably, innate ideas of mind and body. Among the metaphysical theses he develops is that mind and body have wholly distinct essences: the essence of thinking substance is pure thought; the essence of body is pure extension. In a remarkable maneuver, Descartes invokes this distinction to refute the scep