Lactantius

Lucius Caelius (or Caecilius?) Firmianus Lactantius was an early Christian author who wrote in Latin (around A.D. 240 - around 320). Lactantius, a native of North Africa, taught rhetoric in various cities of the eastern half of the Roman Empire, ending in Constantinople. He wrote works explaining Christianity and defending it from pagan philosophers. His Divinae Institutiones ("Divine Institutions") is an early example of a systematic presentation of Christian thought.

Lactantius preserves for us the story of Constantine I's vision of the labarum before his conversion to Christianity.