There is hardly a mistake which in the course of our lives we have committed, but some proverb, had we known and attended to its lesson, might have saved us from it. – Richard Chenevix Trench, Proverbs and Their Lessons, 1905

Reframing an extract as a quotation constitutes a kind of coauthorship. With no change in wording, the cited passage becomes different. I imagine that the thrill of making an anthology includes the opportunity to become such a coauthor. – Gary Saul Morson, The Words of Others: From Quotations to Culture, 2011

QUOTATION, n. The act of repeating erroneously the words of another. The words erroneously repeated. – Ambrose Bierce, The Devil’s Dictionary

Next to the originator of a good sentence is the first quoter of it. Many will read the book before one thinks of quoting a passage. As soon as he has done this, that line will be quoted east and west. – Ralph Waldo Emerson, “Quotation and Originality,” Letters and Social Aims, 1876