The innovative Sienese painters and brothers Ambrogio and Pietro Lorenzetti, although occasional collaborators, usually work independently, each making their own distinctive contributions to the development of Italian painting.

Ambrogio, from 1337 to 1339, executes an enormous (more than forty feet/tweve meters wide) panoramic fresco known as “Allegories of Good and Bad Government” in Siena’s Palazzo Pubblico, depicting in strikingly naturalistic detail secular life in city and country under the beneficent government of his town.

Ambrogio paints the “Purification of the Virgin” in 1342 for the Cathedral of Siena.

Like his brother Pietro's notable altarpiece “Birth of the Virgin,” executed for the cathedral at the same time, space is rendered in a deep and naturalistic style (and anticipates even more closely the vanishing-point perspective developed in fifteenth-century Florence).

Ambrogio’s other representatives of the Virgin—either in depictions of the Annunciation or as the Madonna with a very lively, realistic infant Christ—reflect the homely, down-to-earth approach to Christian mysteries characteristic of the age.