Did Burning Mirrors Cause Body Marks on St. Francis of Assisi?

The present paper aims to question the textual narratives and the visual means which were employed by the Franciscans to increase the credibility of St. Francis’s stigmata. Following the doubts and skepticism which accompanied the Franciscan efforts to monopolize the saintly status of its stigmatized founder through a Seraphic vision, an urgent need to increase credibility has emerged. The study suggests that the Florentine Giotto di Bondone and the Sienese Pietro Lorenzetti employed widely disseminated optical knowledge about burning mirrors to invent a durable and credible iconographic formula of Francis’s stigmatization.