It's the old story of the hotel guest in a small town. Paid $20 for a room and went to get dinner before going to the room. The hotel operator owed the baker $20 so he took the cash and paid her. She owed the hair dresser $20, paid it. Hair dresser owed the florist $20 and paid it. Florist owed the hotelier $20 and so paid that debt. The guest returned from dinner, having made a phone call and discovering plans had changed. Since he had never even gone to the room, he requested a refund, which was cheerfully granted. In this story $100 of debt existed, which was all paid with $20, and that money left town in the same pocket it entered. Is there a flaw in that logic? The answer to your question lies within the story.