Gottfried Leibniz based the symbol on the Latin word summa (“sum”), which he wrote ſumma (with a long s 'ſ' ). This use first appeared publicly in his paper De Geometria, published in Acta Eruditorum of June, 1686, but he had been using it in private manuscripts since at least 1675.
- (mathematics) Denotes the integral
- ^ Mathematics and its History, John Stillwell, Springer 1989, p. 110
- ^ Early Mathematical Manuscripts of Leibniz, J. M. Child, Open Court Publishing Co., 1920, pp. 73–74, 80.