Douglas MacArthur's speech to the Texas Legislature in Austin (June 13, 1951) as quoted in "General MacArthur Speeches and Reports 1908-1964" edited by Edward T. Imparato (p. 175), June 14, 2000.
Speaking to the Roman Senate, as recorded by Sallust in The Catiline War (c. 40 b.c.). This quotation is a favorite of CIA counterintelligence officers.