This painting depicts a historical event from the year 390 when Ambrose, the archbishop of Milan, refused to give communion to Emperor Theodosius I until he made public penance for the massacre of thousands of innocents after an insurrection. Theodosius, the last emperor to command the entire Roman Empire, eventually submitted to the archbishop’s moral authority.

The brushwork and arrangement of figures in this composition showcase Alessandro Magnasco’s fluid, energetic style. However, for the elaborate background edifice, an imaginary interpretation of the atrium of an early Christian church, he most likely employed an unidentified specialist in architectural painting.