Lactantius, LUCIUS CÆLIUS (or CÆCILIUS) FIRMIANUS, an eminent Christian apologist who flourished in the early part of the 4th century. His Italian descent is more than dubious, but it is certain that he was brought up in Africa, although it is very unlikely that he was a pupil of Arnobius. He seems to have settled as a teacher of rhetoric in Nicomedia in Bithynia, and most likely he was converted there by witnessing the marvellous constancy of the Christian martyrs under the tenth and most savage persecution of Diocletian. About the year 313 he was invited to Gaul by Constantine the Great, to act as tutor to his son Crispus, and is supposed to have died about 325. His principal work is his Divinarum Institutionum libri vii., a production both of a polemical and apologetic character. His theology is somewhat crude, and he has been accused of error in his treatment of the doctrine of the Holy Spirit—his Chilianism and his eschatology were not peculiar to himself. Among his other writings are treatises De Ira Dei and De Mortibus Persecutorum, both inscribed to his dear friend, the famous Donatus. His style is remarkably pure, justifying his title of the 'Christian Cicero.' His character appears to have been elevated but austere, perhaps somewhat soured by the poverty and trials of his life.
Lactantius was remarkably popular in the middle ages, and MSS. and printed editions of his works are numerous. Dufresnoy in his edition (2 vols. 1748) enumerates as many as 86 editions of his entire works, besides separate editions of his different treatises, from 1461 to 1739 A.D. The best editions are those in vols. x.-xi. of the Bibl. Pat. Eccl. Lat. by Gersdorf (Leip. 1842-44), and Migne's Patrologia (vol. vi. 1844). There is a translation in Clark's Ante-Nicene Library.