The body is akin to a corpse, or rather, a host for the soul. Yet, the body needs to be taken care of, as the soul is intertwined within it. Thus, the senses alert the soul about potential harm and the needs of the body so that the soul can nourish it. 

Essence is the most fundamental nature of a substance and is what constitutes its definition. For the human subject, it is thinking. For God, it is existence itself.

How something comes into the world as a knowable entity. The existence of himself and God are Descartes’s primary interests.