plenty as blackberries

Mr. [Percy Bysshe] Shelley, your reason? Were this pressed hard upon you, you would probably with [John] Falstaff exclaim, "If reasons were as plenty as black-berries, I would not give you one upon compulsion!"

1938, Newman Ivey White, “Queen Mab [A Radical Seeks Shelter (William Clark’s Reply to … Queen Mab, 1821)]”, in The Unextinguished Hearth: Shelley and His Contemporary Critics, Durham, N.C.: Duke University Press, →OCLC, chapter I (Anti-matrimonial Thesis of Queen Mab), page 73