I happened to be watching a New York Knicks game on television the other night when the revolving billboard beneath the scorer's table unfurled an advertisement for Propecia, the Merck drug that prevents hair loss. In one of those Proustian leaps of association that often come to me while I'm in couch-potato mode, I found myself thinking about April showers, and mosquitoes, and medicine. The connection may seem circuitous, but hang on-we'll get there.

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