Just because the person is so immersed in a dream that it is impossible for him or her to recognize the disparities between these 2 experiences, can that same person still distinguish the difference once he or she wakes up. Furthermore, a clear sensation like pain cannot be the same as the pain we feel upon waking, some argue. After all, Descartes' premise is based on the idea that there is nothing in reality that a dream cannot replicate so vividly that it cannot be distinguished. But he also said that dreams borrow, in a sense, some things from reality, but not all, so these may be nothing more than somewhat plausible events invented by our dreams.