Aristotle (c. 384-322 BCE)
“Anything that we have to learn to do we learn by the actual doing of it: people become builders by building and instrumentalists by playing instruments. Similarly we become just by performing just acts, temperate by performing temperate ones, brave by performing brave ones.”
- From The Nicomachean Ethics (Book II, chapter I) by Aristotle, translated by J. A. K. Thomson (Penguin Classics, 2004).