Back to Methuselah pt. 1, act 1 (1921). This was a favorite quotation of Robert F. Kennedy's, and Edward M. Kennedy used it in his eulogy of Robert Kennedy.
Margaret Thatcher's speech at 1981 Sir Robert Menzies lecture at Blackwood Hall of Monash University in Melbourne, www.margaretthatcher.org. October 6, 1981.
United States. President (1945-1953 : Truman), Harry S. Truman (1962). “Harry S. Truman: Containing the Public Messages, Speeches, and Statements of the President, 1945-53”