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Imagine you own a thriving shop. You offer the best prices. People travel miles to buy your wares, and you've been making substantial profits. You have one customer in particular who is extremely reliable. Problem is, for some years you have had to lend him the money to buy stuff from the shop, usually out of the profits you make from him. He's happy to borrow, and you're content to hold on to his IOUs because he's never reneged on a debt. But lately your best punter has been getting some gip at home. Some family members are worried that they owe too much to the shopkeeper, and wonder whether he is being manipulative. Deep down, you, the shopkeeper, begin to doubt the wisdom of holding all those IOU's.