Everybody is selling a secret, and nobody is giving one away — but a man chained to a Roman soldier writes to his friends and says he has learned one, then hands it over in a thank-you note. This final message in Philippians looks at the contentment Paul found in a prison cell: not the absence of desire, but a heart so satisfied by Christ that it stops grasping. Paul learned it in two classrooms — plenty and hunger — and insists no one is born knowing it. We trace how the secret is learned, how it turns out to be a person, and how it leaks into his friendships, their generosity, and even Caesar's household. Fittingly, on a Sunday of baptism and the Lord's Supper, the letter that opened with grace closes with it.