Celso Sozzini

Celso Sozzini (1517–1570) was an Italian freethinker, brother of Alessandro (father of Fausto), Lelio, Cornelio, Dario, and Camillo.Giampaolo Zucchini Celso e Camillo Sozzini nel gruppo ereticale familiare : Nuovi documenti in Svizzera, 1561-1570 Bologna 1981.[http://www.borgoscopetorelais.it/en/relais.html Borgo Scopeto] {{webarchive|url=https://web.archive.org/web/20100609185710/http://www.borgoscopetorelais.it/en/relais.html |date=2010-06-09 }} "At the beginning of the 4th century some members of the Sozzini were already participating in the magistrature of the Sienese Republic, but it is only towards the end of the 15th century and during the 16th that Cornelio, Dario, Lelio, Camillo and Fausto assembled, with great enthusiasm, the theses for reform which spread throughout many scholarly academies."

Celso's father Mariano Sozzini il giovane (1482–1556) had eleven sons and two daughters. Alessandro, father of Fausto Sozzini, was the eldest but died young.

Celso first taught in Siena,Paul F. Grendler The universities of the Italian Renaissance 2002 section "4 1.123 Celso Sozzini (1517-70) initially taught at Siena..." and was founder of the short-lived Accademia del Sizienti (1554) of Bologna,Accademia dei Sizienti di Bologna, v. Sbaragli L. XLIX, 1942, pp. of which young Fausto was a member.