Epiphanius, tom. i. Haeres. lxxii. 4, p. 837. See the adventures of Marcellus, in Tillemont (Mem. Eccles. tom. vii. p. 880-899). His work, in one book, of the Unity of God, was answered in the three books, which are still extant, of Eusebius. After a long and careful examination, Petavius (tom. ii. 1. i. c. 14, p. 78) has reluctantly pronounced the condemnation of Marcellus.