Emperor Theodosius II commissioned and published the Codex Theodosianus, or Theodosian Code, in 439. It is a large anthology of legal issuances and statements from as far back as the era of Constantine, sole ruler of the empire from 324 to 337, and the latest sources come from the time of Theodosius II himself. The selections translated here were, in their own times, written in different contexts and sent to different audiences. There are edicts, made for a more general audience and applicable to many; there are decrees, which arise from the adjudication of a specific case; and there are letters written to specific city, provincial, and imperial officials, containing orders from one or another emperor. Yet as parts of this anthology, they are presented as having equal weight and equal applicability; they are statements by emperors, which establish a precedent of law, presented in this “Code” and accessible to officials and judges for consultation.

Ambrose’s tenure as metropolitan bishop of an imperial capital brought him into considerable contact with the eastern emperor Theodosius I, who frequently resided in Milan during his visits to the West, especially from 388 to 391. Ambrose’s engagement with the emperor was confrontational. For instance, early in his stay, at a church service, Theodosius sought to take communion with the priests at the altar, as was the custom in Constantinople, but according to the church historian Sozomen (Ecclesiastical History 7.25.9), Ambrose told him to return to his seat. This was a harbinger of the complex power dynamic that would characterize the relationship between emperor and bishop in the coming years. In 390, after a general was murdered by rioters in the city of Thessalonica, troops were let loose on the city’s residents, many of whom were slaughtered.