What status and place could it give to an event that really happened (even if in Descartes' writing the personal pronoun 'I' allows anyone to repeat it), an event which meant that a man sitting by the fire, his eyes fixed on his paper, accepted the risk of dreaming that he was a man asleep, who was dreaming that he was seated by the fire, his eyes fixed on a piece of paper, but refused the risk of seriously imagining that he was a madman imagining that he was seated by the fire, reading or writing?