In the meantime, the Arians, not secretly, as before, but openly and publicly proclaimed their monstrous heretical doctrines. Moreover, they interpreted after their own views the Synod of Nicæa, and by the addition of one letter to its finding, threw a sort of obscurity over the truth. For where the expression Homoousion had been written, which denotes “of one substance,” they maintained that it was written Homoiousion, which simply means “of like substance.” They thus granted a likeness, but took away unity; for likeness is very different from unity; just as, for illustration's sake, a picture of a human body might be like a man, and yet possess nothing of the reality of a man.
But some of them went even farther, and maintained Anomoiousia, that is, an unlike substance. And to such a pitch did these controversies extend, that the wide world was involved in these monstrous errors. For Valens and Ursatius, with their supporters, whose names we have stated, infected Italy, Illyria, and the East with these opinions. Saturninus, bishop of Arles, a violent and factious man, harassed our country of Gaul in like manner. There was also a prevalent belief that Osius from Spain had gone over to the same unfaithful party, which appears all the more wonderful and incredible on this account, that he had been, almost during his whole life, the most determined upholder of our views, and the Synod of Nice was regarded as having been held at his instigation.
If he did go over, the reason may have been that in his extreme old age (for he was then more than a centenarian, as St. Hilarius relates in his epistles) he had fallen into dotage. While the world was disturbed by these things, and the churches were languishing as if from a sort of disease, an anxiety, less exciting indeed, but no less serious, pressed upon the emperor, that although the Arians, whom he favored, appeared the stronger, yet there was still no agreement among the bishops concerning the faith.
Source: Sacred History (New Advent)