But further, in order to embellish it with flowers of language and gems of thought, it is not necessary for this ornamentation to be spread evenly over the entire speech, but it must be so distributed that there may be brilliant jewels placed at various points as a sort of decoration. – Cicero, De oratore

The borrowing is often honest enough, and comes of magnanimity and stoutness. A great man quotes bravely and will not draw on his invention when his memory serves him with a word as good. – Ralph Waldo Emerson, “Quotation and Originality,” Letters and Social Aims, 1876