This monumental, line-by-line commentary makes Thomas Aquinas's classic Treatise on Happiness and Ultimate Purpose accessible to all readers. Budziszewski illuminates arguments that even specialists find challenging: What is happiness? Is it something that we have, feel, or do? Does it lie in such things as wealth, power, fame, having friends, or knowing God? Can it actually be attained? This book's luminous prose makes Aquinas's treatise transparent, bringing to light profound underlying issues concerning knowledge, meaning, human psychology, and even the nature of reality.