Source, in full
Gotthold Ephraim Lessing, as quoted in The London Medical Gazette Vol. V (1847), p. 1118; and Gotthold Ephraim Lessing: His Life and His Works (1878) by Helen Zimmern, p. 443 In "Grand dame of letters who's not going quietly", The Times (London, 23 November 2003), the phrase is unattributed, but interviewer Amanda Craig says it is Doris Lessing's own "motto".