Source
Samuel Johnson, *The History of Rasselas, Prince of Abissinia* (1759), Chapter XII ("The Story of Imlac Continued")
Editorial Note
Tracing this line back to the text of Johnson's *Rasselas* (1759), in Chapter XII, spoken by the character Imlac, where the wording matches exactly: "Few things are impossible to diligence and skill. Great works are performed not by strength, but perseverance." A competing lead pointed toward Samuel Taylor Coleridge's *Biographia Literaria*, but that passage is a different sentiment in different words and does not displace Johnson's documented authorship of this exact construction. Because the phrasing appears verbatim in a work Johnson himself published, the attribution is verified.