First edition of this important collection of a substantial number of Leibniz’s letters and other unpublished writings. The first volume contains the Leibniz-Clarke correspondence and the second the Leibniz-Conti-Newton controversy about the invention of the calculus. This edition is identical with the Du Sauzet edition of the same place and year, the names Duvillard et Changuion being printed on small slips pasted on the title-pages (and ‘Chez H. Du Sauzet’ still visible beneath them when held up to the light). Later editions were published in Hamburg in 1734, Amsterdam in 1740 and Lausanne in 1759.