Didactic and polemical writers quote passages from others to support themselves by authority or to provide themselves with something to controvert; critics quote from the books they examine in illustration of their estimates. These are matters of business on which no general advice need be offered. But the literary or decorative quotation is another thing. A writer expresses himself in words that have been used before because they give his meaning better than he can give it himself, or because they are beautiful or witty, or because he expects them to touch a chord of association in his reader, or because he wishes to show that he is learned and well read. Quotations due to the last motive are invariably ill-advised; the discerning reader detects it and is contemptuous; the undiscerning is perhaps impressed, but even then is at the same time repelled, quotations being the surest road to tedium; the less experienced a writer is, and therefore on the whole the less well-read he is also, the more is he tempted to this error; the experienced knows he had better avoid it; and the well-read, aware that he could quote if he would, is not afraid that readers will think he cannot. Quoting for association’s sake, has more chance of success, or less certainty of failure; but it needs a homogeneous audience; if a jest’s prosperity lies in the ear of him that hears it, so too does a quotation’s; to each reader those quotations are agreeable that neither strike him as hackneyed nor rebuke his ignorance by their complete novelty, but rouse dormant memories; quotations, then, should be adapted to the probable reader’s degree of cultivation; which presents a very pretty problem to those who have a mixed audience to face; the less mixed the audience, the safer is it to quote for association. Lastly, the saying wise or witty or beautiful with which it may occur to us to adorn our own inferior matter, not for business, not for benefit or clergy, not for charm of association, but as carvings on a cathedral façade, or pictures on the wall, or shells in a bowerbird’s run, have we the skill to choose and place them? Are we architects, or bric-à-brac dealers, or what?
—Henry Watson Fowler
A Dictionary of Modern English Usage