On the table was a candle that had been knocked on its side, and where it had been burning there was a little black hole in the table cloth.
The house was empty. The house could have burned down, but it didn’t. A cat knocked down the candle, but it was the people who left the candle on that were responsible for the burn.
When the people came home, they saw the burned tablecloth and the knocked over candle. They never forgot to put a candle out again.
Later, it was election day, and they forgot to vote.