Father Knox's Decalogue
AKA the "10 Commandments of Detective Fiction"
By Monsignor Ronald A. Knox
preface to Best Detective Stories of 1928-29
Ronald Arbuthnott Knox (17 February 1888 – 24 August 1957) was an English Catholic priest, theologian and author of detective stories. He was also a writer and a regular broadcaster for BBC Radio.
Knox belonged to the Detection Club, a society peopled by such legendary mystery writers as Agatha Christie, Dorothy Sayers, G. K. Chesterson, and E. C. Bentley. Among his novels: The Viaduct Murder, Double Cross Purposes, Still Dead.