Horatio Nelson's advice to his Midshipmen (1793) as quoted in "Memoirs of the Life of Vice-Admiral, Lord Viscount Nelson, K.B., Duke of Bronte, Etc., Etc., Etc, Volume 2" edited by Thomas Joseph Pettigrew (p. 580), 1849.
Attributed to Locker's Greenwich Gallery article "Torrington" in Captain Alfred Thayer Mahan "The Life of Nelson, Volume 2: The Embodiment of the Sea Power of Great Britain" (p. 52), 1897.