other · 356 · Antioch
For a generation after Nicaea most eastern bishops were neither Arian nor Nicene but somewhere between, and the middle held because nobody defined it too closely. Aetius destroyed that. A Syrian of poor family who had been a goldsmith and a physician before he was a theologian, he argued with the confidence of a logician that the Son is anomoios, unlike the Father — not merely subordinate, not merely of similar substance, but of a different kind — and that God's essence is comprehensible, being simply unbegottenness. His pupil Eunomius carried it further and wrote it down. The effect was not to win the argument but to end it: once the position was stated nakedly, the men in the middle discovered they were closer to Athanasius than to this, and the reaction that followed produced the settlement of 381. Both men were exiled repeatedly, and Aetius was briefly rehabilitated by Julian, who liked anyone the church had thrown out. He is here because the shape of the fourth century is not intelligible without him: the extreme is what made the centre choose.
Why did the moderate position collapse?
Because the radicals said the quiet part out loud, and after that there was no middle.