FIRMICUS, MaternusJulius, the name of a Latin writer, and most probably of two, who lived in the reign of Constanøue and his successors. About the year 347 one of them composed a work entitled De Erroribus Profanarum Religionum, which he inscribed to Constantius and Constans, the sons of Constantine, and which is still extant. During the life of Constantine a person of the same name as the author of the work on Christianity commenced his eight books on astronomy, which were not completed however till 354 b.c. They were first printed by Aldus Manutius in 1501, and have been reprinted several times since. The work is interfused with NeoPlatonic philosophy, and its spirit is hostile to Christianity. Its diction in some cases resembles that of the Christian work, but it is impossible that two works so contradictory in tone and spirit could have been written by the same person at the same period; and even if it be supposed, contrary to the evidence, that the Christian work was written subsequent to the heathen one, all the contradictions between them would not be accounted for.

The Christian work is preserved in a Palatine MS. in the Vatican library. It was first printed at Strasburg in 1562, and has been reprinted several times, both separately and along with the writings of Minucius Felix, Cyprian, or Arnobius. The most correct editions are those by Conr. Bursian, Leipsic, 1856, and by C. Halm, in his Minucius Felix, Vienna, 1867.