The quotation-business is booming. No subdivision of the culture seems too narrow to have a quotation book of its own…. It would be an understatement to say that these books lean on one another. To compare them is to stroll through a glorious jungle of incestuous mutual plagiarism. – James Gleick, 1993

Seek not to know who said this or that, but take note of what has been said. – Thomas à Kempis, The Imitation of Christ, translated from Latin

A learned historian declared to me of a contemporary, that the latter had appropriated his researches; he might, indeed, and he had a right to refer to the same originals; but if his predecessor had opened the sources for him, gratitude is not a silent virtue. – Isaac D’Israeli, “Quotation,” A Second Series of Curiosities of Literature