Final answer:
Aristotle's conception of the four causes is at the center of Descartes' metaphysics.
Step-by-step explanation:
At the center of Descartes' metaphysics is Aristotle's conception of the four causes. Aristotle believed that the nature of anything could be understood by answering four basic questions: material cause, formal cause, efficient cause, and final cause. These causes provide a framework for understanding the essence and purpose of things, which Descartes then built upon in his own philosophical system. For example, Descartes used the concept of the efficient cause to argue for the existence of God as the first cause or prime mover.