Known sourcecanonical
"Though with those streams he no resemblance hold, Whose foam is amber and their gravel gold; His genuine and less guilty wealth t' explore, Search not his bottom, but survey his shore."
Sir John Denham / Cooper's Hill. Line 165.
Cooper's Hill. Line 165.
Bartlett's Familiar Quotations, 9th ed. (Little, Brown, 1905), public domain