In the Meditations, Descartes changed the structure of the argument. In the Second Meditation, he established that he could not doubt the existence of himself as a thinking thing, but that he could doubt the existence of matter. However, he explicitly refused to use this situation to conclude that his mind was distinct from body, on the grounds that he was still ignorant of his nature (7:27). Then, in the Sixth Meditation, having established, to his satisfaction, the mark of truth, he used that