boxing is a sport of beauty and brutality where people float like a butterfly and sting like a bee. but how can it be both the sweet science and the hurt business? a sport of rhythm and bone crushing. for a look in to the fascinating dichotomies i went to gleason's gym in brooklyn to the talk to howard shotz whose new book "at the fights" takes us inside the unique world of professional boxing. >> boxers are different from any other athlete. they choose a profession where they're fighting somebody whose career is advanced by knocking them out. >> right. >> who would do that? where does this come from? what is this courage? what is this heart? >> interesting row of pictures