This same line of reasoning is used to describe the essences and necessary properties of the body and mind. A thinking thing can exist with its unique essence being thought and other modifications (modes) of thinking such as affirming and denying, willing and not wanting. According to Descartes, the mind is conscious and not extended, while the body is extended but not conscious. Descartes uses these essences as evidence that the mind and the body are two completely different things that essentially have nothing in themselves