Of God and His Creatures

Sabellius, an African from the neighbourhood of Cyrene, in the early third century, an anti-Trinitarian, taught that one and the same divine Being as giving the Old Law was called the Father, as born of Mary was called the Son, as given to the Apostles was called the Holy Ghost, so that there were three manifestations, but not what we should call three Persons; and that when God was under one of these manifestations, He was not under either of the other two.

Of God and His Creatures: 4.5