Henry David Thoreau, Jeffrey S. Cramer (2007). “I to Myself: An Annotated Selection from the Journal of Henry D. Thoreau”, p.170, Yale University Press
H. Jackson Brown, Jr. (2012). “Life's Little Instruction Book: Simple Wisdom and a Little Humor for Living a Happy and Rewarding Life”, p.75, Thomas Nelson Inc
Address at the Sorbonne, Paris, 23 Apr. 1910. Richard M. Nixon quoted this passage in his address to the nation announcing his decision to resign the presidency, 8 Aug. 1974. See Theodore Roosevelt 1; Theodore Roosevelt 2; Theodore Roosevelt 5