The Lantern Keeper

A lighthouse keeper maintained three lights: a great beacon, a secondary lamp, and a simple candle in the window.

"Why three?" a visitor asked.

"The beacon is for clear nights. If it fails, the lamp will do. If the lamp fails, the candle will serve. A dim light is better than a dark shore."

"And if the candle fails?"

"Then I stand in the window with a torch. There is always a next step down."