Once upon a time, a street merchant caught a young boy trying to light a candle stump from his brazier.
"You, lad!" roared the trader, "What do you think you are playing at?"
"I'm just getting a light, sir," replied the boy.
"Then you can buy a box of matches for a penny!"
"If I had a penny," said the boy, "I would buy some matches. But I have no money!"
"That does not give you the right to steal!", thundered the merchant.
"Stealing?" The boy was shocked. "If I light this candle from your brazier, your brazier will still be alight!"
"Ah," said the merchant, "But I will be a penny the poorer!"
The boy was perplexed. "How so, sir? Even if I don't take a light with me, you still won't have a penny!"
The merchant laughed. "Aha, child. The knowledge that you have no light is well worth a penny to me!"