Based on the monkeys paw
"Be careful what you wish for" means think about what could happen if you make this wish and think about how it could effect your life.
"Sensible" as described in the story is describing on the person who would throw it in the fire.
When the husband made a wish for two hundred pounds, he believed he would have everything he wanted.
Due to the mans wish he had made his son died because of the wish
A wish can have a good or bad ending based on how you see things.