Maternus Julius, a Latin writer who flourished under the successors of Constantine. About the year 345 he composed a work entitled *De Erroribus Pro- fanarum Religionum*, which he inscribed to Constantius and Constans, the sons of Constantine, and which is happily still extant, accompanied with the annotations of John Wouwer. To Firmicus are also attributed eight books on astronomy, first printed by Aldus Manutius in 1501, and reprinted several times since; but as this work contains nothing relating to the true science of astronomy, and is filled with astrological calculations after the manner of the Babylonians and Egyptians, Baronius doubts whether a good and pious Christian, as Firmicus is represented to have been, could have indulged in such profane and impious speculations. Cave, however, very reasonably supposes that he might have written these books anterior to the date of his conversion from Paganism. Of the treatise on the *Errors of the Profane Religions*, the principal editions subsequent to that of Aldus are, one printed at Strasburg in 1562, another at Heidelberg in 1599, and a third at Paris in 1610, all in 8vo; but afterwards it was conjoined with Minucius Felix, and printed at Amsterdam in 1645, at Leyden in 1652, and again at Leyden by James Gronovius, in 1709, 8vo. It is likewise to be found in the *Bibliotheca Patrum*, and at the end of Cyprian, printed at Paris in 1666. (Dupin; Cave; Moreri; Fabricius, *Bibl. Lat.* and *Bibl. Lat. Med.*)