Jock the Thinner

There was a Scottish tradesman, a painter called Jock -- of course -- who was very interested in making a pound where he could ... so he often would thin down his paint to make it go a wee bit further.
As it happened, he got away with this for some time, but eventually the Church of Scotland decided to do a big restoration job on the roof of one of their biggest churches, Jock put in a tender and because his price was so competitive, he got the job. And so he set to, with a right good will -- erecting the trestles and putting up the planks, and buying the paint and ... yes, I am sorry to say, thinning it down with the turpentine.

Well, Jock was up on the scaffolding, painting away, the job nearly done, when suddenly there was a horrendous clap of thunder, and the sky opened and the rain poured down, washing the thin paint from all over the church and knocking Jock fair off the scaffold to land on the lawn, among the gravestones, surrounded by telltale puddles of the thinned and useless paint.

Jock was no fool. He knew this was a judgement from the Almighty, so he fell on his knees and cried: Oh, God! Forgive me! What should I do?

And from the thunder, a mighty Voice spoke: Repaint! And thin no more!