A form of Winston Churchill's quotation, made in a radio broadcast in October 1939:
- "I cannot forecast to you the action of Russia. It is a riddle, wrapped in a mystery, inside an enigma; but perhaps there is a key. That key is Russian national interest."
- (idiomatic) Something very mysterious and hidden.
- http://www.phrases.org.uk/meanings/31000.html [17 Mar 2009]