inputs/outputs

I went to one of those bookswapping sites today to find a Thomas Frank book.  I searched for stuff that I’d have to trade in order to get it.  I figured with the amount of books I have, there’s bound to be someone who wanted to trade with me.

How many books showed up in my search?  None.  Only video games, and really expensive ones too.  Maybe the people getting rid of the books don’t like to read, and the people getting rid of the games don’t play very much.  It reminded me of trying to put the negative sides of two magnets together.  Granted, this could be a completely isolated instance, but it was intriguing.