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In [https://books.google.com/books?id=Dy8RAAAAIAAJ&pg=PA28&lpg=PA28&dq=Playfair+%22theory+that+explains+everything+explains+nothing%22&ots=j4p-xWU0mp&sig=ACfU3U0lg4F-Ipn2lmUQZoj3IMi-rfB0jQ&hl=en#v=onepage&q=Playfair%20%22theory%20that%20explains%20everyth