Bill, an unscrupulous painter, would often thin down his paint when hired to do a job, and pocket the money he'd save.
One day, the local church decided to do some long-awaited maintenance, and hired Bill for the job.
Bill gets to work, and after a good few hours, he's nearly done - as he stands on his scaffolding to finish off the steeple, he smiles to himself: the paint job looks pretty good, he's scammed the church out of a few hundred bucks, and he'll be done before dinner.
Suddenly, thunder ensues, a huge bolt of lightning knocks Bill right off his scaffolding, and the skies open up - and all of Bill's newly-applied paint washes right off the church.
Bill, a religious man despite his thievery, knows it's a sign from God. He falls to his knees in a puddle of rainwater and paint, and cries, "Oh God, forgive me! What should I do?"
And amongst the thunder, a booming voice: "REPAINT! REPAINT! AND THIN NO MORE!"