"I'm off. I've left the dehumidifer running in the bathroom."
[Exasperated teenage sigh.] "You know, it's never going to dry out the bathroom completely because the toilet's full of water."
"No, but it will help the air dry and that will help the paint dry."
"Didn't you notice that mum had repainted the wall?"
"No." [Pause.] "I did notice the bare patch had gone."
"Did you think it had just healed?"
"By the grace of God, strange things can happen even to walls ..."