Ambrogio Lorenzetti “huomo di grande ingegno”: un polittico fuori canone e due tavole dimenticate.

Ambrogio Lorenzetti's dispersed polyptych in Santa Petronilla and now in the Pinacoteca Nazionale di Siena is among the most debated works in his oeuvre. Its description in an inventory of 1823 allows us to review its vicissitudes prior to the substantial reworking it suffered in the 19th century, and to reconstruct its appearance, including a "nano ed uno sportello in mezzo" at the base of the central register. The female Augustinian connotations go the altarpiece suggests it came from the Sienese nunnery of S. Marta; its mention in documents and the study of the material evidence point to unusual, experimental carpentry that was seemingly made to adapt itself to a comunichino. The work was painted during the artist's maturity, a period starting in the late 1330s with the fresco in the chapter-house of S. Agostino in Siena and the splendid Maestà in Massa Marittima; the reconstruction of the latter is here expanded by two dispersed globes, now in the Fogg Art Museum, Cambridge and the Isabella Stewart Gardner Museum, Boston, each entirely consistent in style and material with the panel in Massa Marittima