Aetius ( Ἀέτιος ), the founder and head of the strictest sect of Arianism, upon whom, on account of the boldness of his reasonings on the nature of God, was affixed the surname of "the ungodly," ἄθεος (Soz. iii. 15). He was the first to carry out the doctrines of Arius to their legitimate issue, and in opposition both to Homoousians and Homoiousians maintained that the Son was unlike, ἀνόμοιος, the Father, from which his followers took the name of Anomoeans. They were also known as Eunomians, from his amanuensis Eunomius. the principal apologist of the party; and as Heterusiasts and Exukontians, as affirming that the Son was ἐξ ἑτέρας οὐσίας from the Father, and created ἐξ οὐκ ὄντων .
The events of his singularly vagrant and chequered career are related from very different points of view by the Eunomian Philostorgius, and the orthodox writers Socrates, Sozomen, Theodoret, and Gregory Nyssen. We must regard Aetius as a bold and unprincipled adventurer, endowed with an indomitable love of disputation, which led him into incessant arguments on the nature of the Godhead, the person of our Lord, and other transcendental subjects, not only with the orthodox but with the less pronounced Arians. He was born at Antioch. His father, dying insolvent, left Aetius, then a child, and his mother in extreme destitution (Philost. H. E. iii. 15; cf. Valesius's notes; Suidas, sub. voc. Ἀέτιος ). According to Gregory Nyssen, he became the slave of a woman named Ampelis; and having obtained his freedom in some disgraceful manner, became a travelling tinker, and afterwards a goldsmith. Having been convicted of substituting copper for gold in an ornament entrusted to him for repair, he gave up his trade, and attaching himself to an itinerant quack, picked up some knowledge of medicine. He met with a ready dupe in an Armenian, whose large fees placed Aetius above the reach of want. He now began to take rank as a regular and recognized practitioner at Antioch (Greg. Nys. adv. Eunom. lib. i. vol. ii. p.293). Philostorgius merely tells us that he devoted himself to the study of philosophy and dialectics, and became the pupil of Paulinus the Arian bishop, recently removed from Tyre to Antioch, c. 323 (Philost. iii. 15). Aetius attached himself to the Aristotelian form of philosophy, and with him, Milman remarks ( Hist. of Christianity , vol. ii. p.443) the strife between Aristotelianism and Platonism among theologians seems to have begun. His chief study was the Categories of Aristotle, the scope of which, according to Socrates (H.E. ii. 35), he entirely misconceived, drawing from them sophistical arguments repudiating the prevailing Platonic mode of argument used by Origen and Clemens Alex. On the death of Paulinus his protector, c. 324, he was banished to Anazarbus in Cilicia, where he gained his livelihood by his trade. Here his dialectic skill charmed a grammarian, who instructed him more fully, receiving repayment by his menial services. Aetius tried his polemic powers against his benefactor, whom he put to public shame by the confutation of his interpretation of Scripture. On the ignominious dismissal which naturally followed, Athanasius, the Arian bishop of the place, opened his doors to the outcast, and read the Gospels with him. Aetius also read St. Paul's Epistles at Tarsus with Antonius, who, like Athanasius, was a disciple of Lucian, Arius's master. On Antonius's elevation to the episcopate, Aetius returned to Antioch, where he studied the prophets, particularly Ezekiel, with Leontius, afterwards bishop of that see, also a pupil of Lucian. A storm of unpopularity soon drove him from Antioch to Cilicia; but having been defeated in argument by one of the Borborian Gnostics, he betook himself to Alexandria, where he soon recovered his character as an invincible adversary by vanquishing the Manichean leader Aphthonius. Aphthonius, according to Philostorgius ( H. E. iii. 15), only survived his defeat seven days. Here Aetius took up his former professions, studying medicine and working as a goldsmith.
On the return of St. Athanasius to Alexandria in 349, Aetius retired to Antioch, of which his former teacher Leontius was now bishop. By him Aetius was ordained deacon, c. 350 (Philost. iii. 17; Socr. H. E. ii. 35; Athan. de Synod. Â§ 38, Ox. trans. p 137; Suidas, s.v. ). His ordination was protested against by Flavian and Diodorus, and he was inhibited from the exercise of his ministry (Theod. H. E. ii. 24). Epiphanius erroneously asserts that he was admitted to the diaconate by George of Cappadocia, the intruding bp. of Alexandria (Epiph. Haeres. lxxvi. 1). Aetius now developed more fully his Anomoean tenets, and he exerted all his influence to induce the Arian party to refuse communion with the orthodox. He also began to withdraw himself from the less pronounced Arians (Socr. H. E. ii. 359). This schism in the Arian party was still further developed at the first council of Sirmium, A.D. 351, where he attacked the respectable semi-Arian (Homoiousian) bishops, Basil of Ancyra and Eustathius of Sebaste (Philost. H. E. iii. 16), reducing them to silence. Exasperated by his discomfiture, Basil denounced Aetius to Gallus. His life was spared at the intercession of bp. Leontius; and being subsequently introduced to Gallus by Theophilus Blemmys, he was sent by him to his brother Julian to win him back from the paganism into which he was lapsing. Gallus also appointed him his religious teacher (Philost. H. E. iii. 27; Greg. Nys. u.s. p. 294).
The fall of Gallus in 354 caused a change in the fortunes of Aetius, who returned to Alexandria in 356 to support the waning cause of Arianism. The see of Athanasius was then occupied by George of Cappadocia, under whom Aetius served as a deacon, and when nominated to the episcopate by two Arian bishops, Serras and Secundus, he refused to be consecrated by them on the ground that they had held communion with the Homoousian party (Philost. iii. 19). Here he was joined by his renowned pupil and secretary Eunomius (Greg. Nys. u.s. p. 299; Socr. H. E. ii. 22; Philost. H. E. iii. 20). Greater troubles were now at hand for Aetius. Basil of Ancyra denounced him to the civil power for his supposed complicity in the treasonable designs of Gallus, and he was banished to Pepuza in Phrygia. The influence of Ursacius and Valens procured his recall; but he was soon driven again into exile. The hard irreverence of Aetius, and the determination with which he pushed conclusions from the principles of Arius, shocked the more religious among the Arian party, and forced the bishops to use all measures to crush him. His doctrines were also becoming alarmingly prevalent. "Nearly the whole of Antioch had suffered from the shipwreck of Aetius, and there was danger lest the whole (once more) should be submerged" (Letter of George, bp. of Laodicea, ap. Soz. H. E. vi. 13). A synod was therefore appointed for Nicomedia in Bithynia. A violent earthquake and the intrigues of the court brought about its division into two synods. The West met at Ariminum; the East at Seleucia in Isauria, A.D. 359. The latter separated without any definite conclusion. "The Arians, semi-Arians, and Anomoeans, mingled in tumultuous strife, and hurled anathemas at one another" (Milman, Hist. Christ. iii. c. 8). Whatever triumph was gained rested with the opponents of the Aetians, who appealed to the emperor and the court, and a second general council was summoned to meet at Constantinople (Athan. de Synod. Â§ 10, 12). Of this council Acacius was the leading spirit, but a split occurred among the Anomoean followers of Aetius. The party triumphed, but its founder was sent into banishment, first to Mopsuestia, then to Amblada in Pisidia. Here he gained the goodwill of the savage inhabitants by his prayers having, as they supposed, averted a pestilence (Theod. ii. 23; Soz. iv. 23, 24; Philost. iv. 12; Greg. Nys. u.s. p. 301).
The death of Constantius, A.D. 361, put an end to Aetius's exile. Julian recalled all the banished bishops, and invited Aetius to his court (Ep. Juliana, 31, p. 52, ed. Boisson; Soz. v. 5), and at the instance of Eudoxius (Philost. ix. 4) presented him with an estate in the island of Lesbos. The ecclesiastical censure was taken off Aetius by Euzoius, the Arian bp. of Antioch (ib. vii. 5), who, with the bishop of his party, compiled a defence of his doctrines ( ib. viii. 2). According to Epiphanius ( Haer. u.s. ), he was consecrated bishop at Constantinople, though not to any particular see; and he and Eunomius consecrated bishops for his own party (Philost. viii. 2). On the death of Jovian, A.D. 364, Valens shewed special favour to Eudoxius, between whom and Aetius and Eunomius a schism had arisen. Aetius in disgust retired to his farm in Lesbos (ib. ix.4). The revolt of Procopius once more endangered his life. He was accused to the governor, whom Procopius had placed in the island, of favouring the cause of Valens, A.D. 365â€“366 ( ib. ix. 6). Aetius returned to Constantinople. He was the author of several letters to Constantius and others, filled with subtle disquisition on the nature of the Deity (Socr. ii. 35), and of 300 heretical propositions, of which Epiphanius has preserved 47 (Haer. lxxvi. Â§ 10), with a refutation of each. Hefele, Konz. Gesch. Bd. i.