Well, Bill went out, bought some paint and started painting the church. He discovered that he was using more paint than he expected so he added some thinner to the paint. The paint still covered okay but not as well as it had at first.
Bill was still using more paint than he wanted to so he added still more thinner to the paint. At that point, the paint became too thin cover well but Bill still kept on painting.
All of a sudden, there was a bolt of lightning right next to him as a loud voice from the sky proclaimed, "Repaint and thin no more."