"From the middle of the Nineteenth Century, nearly every modern book on Logic has contained the words: Entia non sunt multiplicanda, præter necessitatem: quoted as if they were the words of William of Ockham. But nobody gives a particular reference to any work of the Singular and Invincible Doctor ... my own fruitless inquisition for the formula, in those works of Ockham which have been printed, has led me to disbelieve that he ever used it to express his Critique of Entities."