IV.--Basil and the Councils, to the Accession of Valens.
Up to this time St. Basil is not seen to have publicly taken an active part in the personal theological discussions of the age; but the ecclesiastical world was eagerly disputing while he was working in Pontus. Aetius, the uncompromising Arian, was openly favoured by Eudoxius of Germanicia, who had appropriated the see of Antioch in 357. This provoked the Semiarians to hold their council at Ancyra in 358, when the Sirmian "Blasphemy" of 357 was condemned. The Acacians were alarmed, and manoeuvred for the division of the general council which Constantius was desirous of summoning. Then came Ariminum, Nike, and Seleucia, in 359, and "the world groaned to find itself Arian." Deputations from each of the great parties were sent to a council held under the personal presidency of Constantius at Constantinople, and to one of these the young deacon was attached. The date of the ordination to this grade is unknown. On the authority of Gregory of Nyssa  and Philostorgius,  it appears that Basil accompanied his namesake of Ancyra and Eustathius of Sebaste to the court, and supported Basil the bishop. Philostorgius would indeed represent the younger Basil as championing the Semiarian cause, though with some cowardice.  It may be concluded, with Maran, that he probably stood forward stoutly for the truth, not only at the capital itself, but also in the neighbouring cities of Chalcedon and Heraclea.  But his official position was a humble one, and his part in the discussions and amid the intrigues of the council was only too likely to be misrepresented by those with whom he did not agree, and even misunderstood by his own friends. In 360 Dianius signed the creed of Ariminum, brought to Caesarea by George of Laodicea; and thereby Basil was so much distressed as henceforward to shun communion with his bishop.  He left Caesarea and betook himself to Nazianzus to seek consolation in the society of his friend. But his feelings towards Dianius were always affectionate, and he indignantly repudiated a calumnious assertion that he had gone so far as to anathematize him. Two years later Dianius fell sick unto death and sent for Basil, protesting that at heart he had always been true to the Catholic creed. Basil acceded to the appeal, and in 362 once again communicated with his bishop and old friend.  In the interval between the visit to Constantinople and this death-bed reconciliation, that form of error arose which was long known by the name of Macedonianism, and which St. Basil was in later years to combat with such signal success in the treatise Of the Spirit. It combined disloyalty to the Spirit and to the Son. But countervailing events were the acceptance of the Homoousion by the Council of Paris,  and the publication of Athanasius' letters to Serapion on the divinity of the two Persons assailed. To this period is referred the compilation by Basil of the Moralia. 
 i. Eunom.
 iv. 12.
 ois Basileios heteros paren sunaspizon diakonon eti taxin echon, dunamei men tou legein pollon propheron, to de tes gnomes atharsei pros tous koinous hupostellomenous agonas. This is unlike Basil. "This may be the Arian way of saying that St. Basil withdrew from the Seleucian deputies when they yielded to the Acacians." Rev. C.F.H. Johnston, De. S. Scto. Int. xxxvi.
 Ep. ccxxiii. S: 5.
 Ep. li.
 Epp. viii. and li.
 360. Mansi, iii. 357-9.
 ethika. "Capita moralia christiana, ex meris Novi Testamenti dictis contexta et regulis lxxx. comprehensa." Fab. Closely connected with these are the Regulae fusius tractatae (horoi kata platos) lv., and the Regulae brevius tractatae (horoi kat' epitomen) cccxiii. (Migne, xxxi. pp. 890-1306) on which see later.
Reference address : https://www.elpenor.org/basil/life-works.asp?pg=12