Keynes believed...
That the great depression wasn't caused by the contraction of the money supply by the private banking institution known as the Federal Reserve. A much more enlightening book about interest, credit etc is "The Monster from Jekyll Island". As for economics, the real issue is who prints the currency, is it private or public? A few people tried interest free public money: - Hitler, JFK, Lincoln Gaddaffi etc.
I guess it's just a coincidence.