In one of F. Scott Fitzerald\u2019s funniest short stories, \u201cHead and Shoulders,\u201d a certifiable genius falls in love with a showgirl. The plot and moral of the story aren\u2019t relevant for today\u2019s email\u2014though the story is highly recommended\u2014instead there is a little passage in it that introduces a concept that is worth thinking about:\u201cI was a \u2018why child. I wanted to see the wheels go around. My father was a young economics professor at Princeton. He brought me up on the system of answering e...