This Sunday's Gospel reading is from Luke 17, telling the familiar story of the ten lepers who came to Jesus for healing. All were healed, but only one of the ten returned to give thanks to God for the miracle, and moreover he was a despised Samaritan. The lesson for us readers seems self-evident: we ought always to actively give thanks to God for the blessings we receive from his hand, and we should not be like the ungrateful nine, denying God the praise he deserves for his grace and mercy. But is that all there is to it? If the story is intended as an exhortation to behave in a certain way, it seems to be missing a key element: motivation. What penalty is there for ingratitude, and conversely, what reward is there for gratitude? The answers to these questions are not easy to find in the story. The key must lie in the very end, where Jesus tells the grateful ex-leper that his faith has made him well. This is not an unusual way for Jesus to end one of these encounters. Do we really understand what he means?