Descartes' wake/sleep contrast is central to his famous Dream Argument, whereby he is can find no conceivable way to differentiate between whether he is either dreaming or awake in their perceptions of the environment. As Descartes states in his Meditation 1: "…and to experiencing in my dreams the very same things, or now and then even less plausible ones, as these insane people do when they are awake. How often does my evening slumber …showed first 75 words of 661 total…

…showed last 75 words of 661 total…once relied on: his senses. Further on, we can see where this leads, as Descartes calls our sensory perceptions into question to prepare the readers for his following arguments in latter Meditations. Once he sets his audience in the right mind-state, he hopes to have erased any doubts of the claims that he will be building up in the next few meditations and prepare his sceptical readers for the metaphysics that he plans to introduce.