This is the first episode in a three-part series on the philosophy of causation. In this episode, we discuss Aristotle's views on causation. Aristotle was one of the most influential philosophers of all time, and even served as Royal Tutor to the young Alexander the Great. Aristotle understood causation as a question about why things change. Why does a block of iron become a knife? Why do lions always grow sharp teeth? Aristotle argued that things change to fulfill their proper purpose and function. In Part Two, we will discuss David Hume's challenge to Aristotle, which upended over a thousand years of philosophy.