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
Books of quotation are not only of importance to the reader for what they contain of matured thought, but also for what they suggest. Our brains receive the spark and become luminous, like inflammable material by the contact of flint and steel. – Maturin M. Ballou, January 1886, preface to Edge-Tools of Speech

