Comedian Soupy Sales tells this joke: A famous art collector is crossing a New York street when, in front of a shop, he sees a shabby cat avidly licking some milk from a small saucer. The man immediately realizes that the saucer is very ancient and very valuable. So he steps into the shop with an uninterested look and asks to buy the cat. But the shop owner answers, "I'm sorry, but the cat is not for sale." "Please," says the collector, "I need a ravenous cat around my house to catch all the mice. I'll give you ten dollars." "The cat is yours," answers the shopowner, taking the money. "Listen," the collector says, "I wonder if for ten dollars more you could also give me that old saucer. The cat seems to like it, and I wouldn't have to use one of mine." "I'm sorry, my friend," the shop owner says, "that little saucer brings me luck. This week I've already sold 68 cats!"