Roger Bacon was a Franciscan friar and an early advocate of the experimental method. He worked on optics, and at the request of Pope Clement IV he wrote a series of books which amounted to an encyclopedia of science. He also worked on alchemy. He kept much of his work secret from his fellow Franciscans, but nonetheless, in 1278 they imprisoned him on the charge of "suspected novelties" in his teaching. In his Letter on the Secret Works of Art and the Nullity of Magic, he wrote "The man is insane who writes a secret in any other way than one which will conceal it from the vulgar and make it intelligible only with difficulty even to scientific men and earnest students. ... Certain persons have achieved concealment by means of letters not then used by their own race or others but arbitrarily invented by themselves."

Further reading at: http://www.thehistorynet.com:80/BritishHeritage/articles/1999/05992_text.htm