— Evelyn Beatrice Hall, livre The Friends of Voltaire
Ch. 7 : Helvetius : The Contradiction, p. 199; because of quote marks around the original publication of these words, they are often attributed to Voltaire, though Hall was not actually quoting him but summarizing his attitude with the expression. The statement was widely popularized when misattributed to Voltaire as a "Quotable Quote" in Reader's Digest (June 1934), but in response to the misattribution, Hall had been quoted in Saturday Review (11 May 1935), p. 13, as stating: I did not mean to imply that Voltaire used these words verbatim and should be surprised if they are found in any of his works. They are rather a paraphrase of Voltaire's words in the Essay on Tolerance — "Think for yourselves and let others enjoy the privilege to do so too."
The paragraph in which the statement first appears reads:
The Friends of Voltaire (1906)
Contexte: 'What a fuss about an omelette!' he had exclaimed when he heard of the burning. How abominably unjust to persecute a man for such an airy trifle as that! "I disapprove of what you say, but I will defend to the death your right to say it," was his attitude now.