Blood was smeared on Jon's math test when he turned it in. The teacher called him up to her desk to see what the problem was. Jon slowly raised his hands into the sight of the teacher. They were red and still bleeding in some places. Jon has OCD, or obsessive-compulsive disorder. Jon's obsession is the uncleanliness of his hands, and his compulsion is to clean them. When he is awake, his hands feel unclean. There is never any dirt on them, and Jon is conscious of this, but he is still obsessed with cleaning the "filth" from them. Every morning he has to get up extra early to scrub his hands for hours, usually going through more than one bar of soap at a time. By the time he is finished, Jon's hands are red and often bleeding, and he is usually late for school. Because of...