Giving up a bad habit
William Penn was once advising a drunkard to give up his habit of drinking intoxicating liquors.
"Can you tell me how to do it?" the man asked.
"Yes, friend." Pen replied. "It is as easy as to open thy hand."
"Convince me of that," the drunkard explained, "and I will promise upon my honour to do as you tell me."
"Well, my friend, when thou findest any vessel of intoxicating liquor in thy hand, open the hand that contains it before it reaches thy mouth, and thou wilt never be drunk again."
This plain advice so delighted the drunkard that he straightway proceeded to follow it.