I forget where I came across a link to Emerson’s essay “Quotation and Originality” (first given as a lecture in 1859), but as Emerson himself would tell you, it doesn’t really matter. He’s not an especially disciplined thinker — he argues every side of the question and doesn’t really come to a conclusion — but he’s always worth reading, and I like this paragraph in particular:
There is, besides, a new charm in such intellectual works as, passing through long time, have had a multitude of authors and improvers. We admire that poetry which no man wrote, — no poet less than the genius of humanity itself, — which is to be read in a mythology, in the effect of a fixed or national style of pictures, of sculptures, or drama, or cities, or sciences, on us. Such a poem also is language. Every word in the language has once been used happily. The ear, caught by that felicity, retains it, and it is used again and again, as if the charm belonged to the word and not to the life of thought which so enforced it. These profane uses, of course, kill it, and it is avoided. But a quick wit can at any time reinforce it, and it comes into vogue again. Then people quote so differently one finding only what is gaudy and popular; another, the heart of the author, the report of his select and happiest hour; and the reader sometimes giving more to the citation than he owes to it. Most of the classical citations you shall hear or read in the current journals or speeches were not drawn from the originals, but from previous quotations in English books; and you can easily pronounce, from the use and relevancy of the sentence, whether it had not done duty many times before, — whether your jewel was got from the mine or from an auctioneer. We are as much informed of a writer’s genius by what he selects as by what he originates. We read the quotation with his eyes, and find a new and fervent sense; as a passage from one of the poets, well recited, borrows new interest from the rendering. As the journals say, “the italics are ours.” The profit of books is according to the sensibility of the reader. The profoundest thought or passion sleeps as in a mine until an equal mind and heart finds and publishes it. The passages of Shakspeare that we most prize were never quoted until within this century; and Milton’s prose, and Burke, even, have their best fame within it. Every one, too, remembers his friends by their favorite poetry or other reading.
More on the subject at Love and Theft.