The ancients, who in these matters were not perhaps such blockheads as some may conceive, considered poetical quotation as one of the requisite ornaments of oratory. – Isaac D’Israeli, “Quotation,” A Second Series of Curiosities of Literature

[T]here are aphorisms that, like airplanes, stay up only while they are in motion. – Vladimir Nabokov, The Gift, 1963, translated from Russian by Michael Scammell

Proverbs accordingly are somewhat analogous to those medical Formulas which, being in frequent use, are kept ready-made-up in the chemists’ shops, and which often save the framing of a distinct Prescription. – Richard Whately, Elements of Rhetoric

The adventitious beauty of poetry may be felt in the greater delight which a verse gives in happy quotation than in the poem. – Ralph Waldo Emerson, “Art”