Besides, it happens (how, I cannot tell) that an idea launched like a javelin in proverbial form strikes with sharper point on the hearer’s mind and leaves implanted barbs for meditation… – Desiderius Erasmus, Adages

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

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