The End (Or Purpose) Is A Cause – Final Cause

St. Thomas Aquinas, Commentary On Metaphysics, Book 5, L. 2, Definition of Cause: “For to ask why or for what reason is to ask about a cause, because when we are asked why or for what reason someone walks, we reply properly by answering that he does so in order to be healthy. And when we answer in this way we are stating a cause. Hence it is evident that the end [or purpose] is a cause.”