PASCAL (Bl.). Traité du triangle. Paris, G. Desprez, 1665, i - Lot 11

PASCAL (Bl.). Traité du triangle. Paris, G. Desprez, 1665, in-4°, stiff ivory vellum, corded, smooth spine with handwritten date and place of printing, natural edges (17th-century binding). Collation: (2) ff. (Title, Avertissement and Table) n. ch. n. sign., 1 folded out-of-text plate, 12 pp. ch. 1-[12] sign. A6, 8 pp. ch.1-8 sign. A4, 16 pp. ch. 1-16 sign. A-B4 and 48 pp. ch. 1-48 sign. A-F4. ORIGINAL EDITION, rare. Published posthumously, it consists of eleven treatises, the first five in French and the last 6 in Latin. This set was found printed in Pascal's papers (1623-1662) after his death. "The heart of his subject is occupied by the figure of the "arithmetic triangle", a tabular presentation that arranges numbers in rows and columns according to given rules of progression, constituting what Pascal calls "numerical orders" and corresponding to the old "figurative numbers"... This arrangement is in itself nothing revolutionary, and was known to many 16th-century mathematicians; but Pascal's novelty lies in providing a theory of it, through which he sets out the principles of reasoning by recurrence." ([...], Pascal, le coeur et la raison, BN, 2017, n° 70). Superb copy, very pure. The vellum on the second cover was stitched over 4 cm at the time of binding. No endpaper at the beginning of the volume. Trace of a watermark on the last blank leaf. Dimensions: 222 x 167 mm. Provenance: trace of a bookplate detached from the first flyleaf. Tchemerzine, V, p. 61 ("Édition originale, très rare"); Maire (A.), Bibliographie générale des oeuvres de Blaise Pascal, I, Pascal Savant, pp. 108-113; Brunet, IV, 401; Hook (D. H.) - Norman (J. M.), The Haskell F. Norman Library of Science & Medicine, 1991, II, 1651 ("Pascal was the first to make a comprehensive study of the arithmetical triangle..."); Klein, pp. 272-273; D.S.B., 9 & 10, pp. 330-342.