The friendship with Amphilochius seems to have begun at the time when the young advocate accepted the invitation conveyed in the name of Heracleidas, Ep. cl. his friend, and repaired from Ozizala to Cæsarea.  The consequences were prompt and remarkable.  Amphilochius, at this time between thirty and forty years of age, was soon ordained and consecrated, perhaps, like Ambrose of Milan and Eusebius of Cæsarea per saltum, to the important see of Iconium, recently vacated by the death of Faustinus.  Henceforward the intercourse between the spiritual father and the spiritual son, both by letters and by visits, was constant.  The first visit of Amphilochius to Basil, as bishop, probably at Easter 374, not only gratified the older prelate, but made a deep impression on the Church of Cæsarea. Epp. clxiii., clxxvi.  But his visits were usually paid in September, at the time of the services in commemoration of the martyr Eupsychius.  On the occasion of the first of them, in 374, the friends conversed together on the doctrine of the Holy Spirit, now impugned by the Macedonians, and the result was the composition of the treatise De Spiritu Sancto.  This was closely followed by the three famous canonical epistles, Epp. clxxxviii., cxcix., ccxvii. also addressed to Amphilochius.  Indeed, so great was the affectionate confidence of the great administrator and theologian “Pace Eunomii,” whom Greg. of Nyssa quotes.  C. Eunom. i. in his younger brother, that, when infirmities were closing round him, he asked Amphilochius to aid him in the administration of the archdiocese. Ep. cc., cci.