The Persistent Messenger

A messenger was sent to deliver a letter to a lord who was often away from his castle.

He arrived. The lord was out. He waited an hour and tried again. Still away.

Another messenger would have waited another hour. This one waited two hours. Then four. Then eight.

"Why do you space your visits so?" the gatekeeper asked.

"If the lord is away for a short while, I'll catch him soon. If he's away for longer, my constant knocking only annoys his household without helping me. I must balance persistence with patience."

On his fifth visit, sixteen hours after the fourth, the lord had returned.