At the end of St John's Gospel, we are told that if everything Christ did during his brief earthly life were written down, the entire world would not contain the books. We can infer, therefore, that many of Christ's miracles and encounters were not recorded in the New Testament.
So why did St Luke include the miracles of curing the leper? Clearly because of the lesson that Christ teaches us by it: the beauty of gratitude.
The one leper who came back to thank Jesus is praised for this gratitude. We can almost hear the sadness in Christ's heart at the lack of gratitude in the other nine who were healed. Why does Christ value gratitude so much? Is he vain? Is his self-esteem so weak that he gets depressed if we don't praise and thank him?
No. He values gratitude because gratitude is valuable - it's valuable for us, for the health of our souls.
In the first place, gratitude keeps us grounded in the truth, which is key for our ongoing relationship with God. In the second place, gratitude is the perfect antidote to sin. Sin turns us in on ourselves, like an ingrown toenail; gratitude opens us up to God and neighbour.
Gratitude is one of the most beautiful flowers in the garden of virtue - what a pity that it's so rare!
Fr. Paulus Waris Santoso, O.Carm