"What are the facts? Again and again and again - what are the facts? Shun wishful thinking, ignore divine revelation, forget what 'the stars foretell,' avoid opinion, care not what the neighbors think, never mind the unguessable 'verdict of history' - what are the facts, and to how many decimal places? You pilot always into an unknown future; facts are your only clue. Get the facts!"
Robert A. Heinlein, The Notebooks of Lazarus Long