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
Dr. Robert C. Worstell, Dorothea Brande, Eark Nightingale, Claude M. Bristol, Napoleon Hill (2017). “Mindset StackingTM Inspirational Journal VolumeSS02”, p.38, Lulu.com