“The wise know their limitations; the foolish do not.”

Source: Nature of Man and His Government (1959), p. 81

Source: The Fry Chronicles

Engaged Buddhism, Social Change and World Peace (2014)

Attributed to Chesterfield by George Agar-Ellis, 1st Baron Dover, in his 1833 edition of Horace Walpole's letters to Sir Horace Mann, such statements have been attributed to many others, such as Lord Chief Justice Campbell, William Henry Maule (in the form "You silly old fool, you don't even know the alphabet of your own silly old business"), Sir William Harcourt, Lord Pembroke, Lord Westbury, and to an anonymous judge, and said to have been spoken in court to Garter King at Arms, Rouge Dragon Pursuivant, or some other high-ranking herald, who had confused a "bend" with a "bar" or had demanded fees to which he was not entitled. George Bernard Shaw uses it in Pygmalion (1912) in the form, "The silly people dont [sic] know their own silly business." Similar remarks occur in Charles Jenner's The Placid Man: Or, The Memoirs of Sir Charles Beville (1770): "Sir Harry Clayton ... was perhaps far better qualified to have written a Peerage of England than Garter King at Arms, or Rouge Dragon, or any of those parti-coloured officers of the court of honor, who, as a great man complained on a late solemnity, are but too often so silly as not to know their own silly business." "Old Lord Pembroke" (Henry Herbert, 9th Earl of Pembroke) is said by Horace Walpole (in a letter of 28 May 1774 to the Rev. William Cole) to have directed the quip, "Thou silly fellow! Thou dost not know thy own silly business," at John Anstis, Garter King at Arms. Edmund Burke also quotes such a remark in his "Speech in the Impeachment of Warren Hastings, Esq." on 7 May 1789: "'Silly man, that dost not know thy own silly trade!' was once well said: but the trade here is not silly."
Disputed

New York World-Telegram and Sun (1961)