I always look for a second or third source when quoting. One of those sources will be a book in my library: Bartlett's (giant) Familiar Quotations ...plus quote books (with appendix) for Twain, Dickens, Chesterton, Madeleine L'Engle, and my friend Gudrun "Goodie" Cable's two volumes, Quotidian and Quotidian II. They contain a quote for everyday of the year by a person whose birthday is the day on which they are quoted.
If you are a writer, blogger, curiosity-driven-life-long-learner, write to my friend Goddy Cable and puchase her Quotidian and Quotidian II collections: Rimsky Press, 707 Southeast Twelfth Ave., Portalnd OR 97214. Tell her, "McNair sent me." (Also available on Amazon.)