You grab the rag and begin to wipe the window with soapy water but
nothing will come off the window at all.
In fact, the more you rub, the dirtier the window seems to get! As the window gets dirtier it becomes harder and harder to see in the room. The room begins to look like a painting done with very dark values and very low contrast so objects in the room begin looking similar and it is difficult to tell where one object ends and another object begins. In the gloom you stumble and fall and your wallet falls out of your pocket. Once you find it you notice the wallet feels lighter so you pull it open and peek inside and discover twenty-five cents has been lost (subtract $0.25 from your wallet).
