This is certainly a mistake on Eusebius’ part (see above, note 2), in which he is followed by Jerome (de vir. ill. c. 55). Against the identification of the Christian Ammonius, whose works are mentioned by Eusebius and Jerome, with Ammonius Saccas, may be urged first the fact that the teaching of Ammonius Saccas, as known to us from Porphyry’s Vita Plotini and from other Neo-Platonic sources, is not such as could have emanated from a Christian; and, in the second place, the fact that the Christian Ammonius, according to Eusebius, was the author of more than one important work, while Longinus (as quoted by Porphyry in the Vita Plot. c. 20) says explicitly that Ammonius Saccas wrote nothing. It is clear from Eusebius’ words that his sole reason for supposing that Ammonius Saccas remained a Christian is the existence of the writings to which he refers; and it is quite natural that he and others should erroneously attribute the works of an unknown Christian of Alexandria, named Ammonius, to the celebrated Alexandrian philosopher of the same name, especially since it was known that the latter had been a Christian in his youth, and that he had been Origen’s teacher in his mature years. We know nothing about the life of the Christian Ammonius, unless he be identified with the presbyter Ammonius of Alexandria, who is said by Eusebius to have perished in the persecution of Diocletian. The identification is possible; but even if it be accepted, we are helped very little, for is only the death, not the life, of the presbyter Ammonius with which Eusebius acquaints us. Ammonius’ writings, whoever he may have been, were well known in the Church. Eusebius mentions here his work On the Harmony of Moses and Jesus (περὶ τῆς Μωϋσέως καὶ ᾽Ιησοῦ συμφωνίας), and in an epistle addressed to Carpianus (see above, p. 38 sq.) speaks of a Diatessaron or Harmony of the Four Gospels (τὸ διὰ τεσσ€ρων εὐαγγέλιον), composed by Ammonius. Jerome mentions both these works (de vir. ill. 55), the latter under the title Evangelici Canones. He refers to these Canones again in his preface to the Four Gospels (Migne’s ed., Vol. X. 528); and so does Victor of Capua. The former work is no longer extant, nor have we any trace of it. But there is extant a Latin translation of a Diatessaron which was made by Victor of Capua, and which was formerly, and is still, by many scholars supposed to be a version of this work of Ammonius. By others it is thought to be a translation of Tatian’s Diatessaron. For further particulars, see above, Bk. IV. chap. 29, note 11.