The text you're looking for, ( On the Happy Life ), is one of St. Augustine's earliest philosophical dialogues. Written shortly after his conversion in 386 AD, it explores the idea that true happiness consists in the knowledge and possession of God. Online PDF & Text Resources
He poses a simple definition: "He is happy who has God." augustine on the happy life pdf
Augustine is not saying happiness is a euphoric feeling. He means a stable, joyful orientation of the whole person toward Truth. The text you're looking for, ( On the