St. Leo the Great Sermon 24 V. Other heresies contain some portion of truth, but the Manichæans contain none whatever

Other heresies, dearly beloved, although they are all rightly to be condemned in their variety, yet have each in some part of them that which is true. Arius, in laying down that the Son of God is less than the Father and a creature, and in thinking that the Holy Spirit was like all else made by the same (Father), has lost himself in great blasphemy; but he has not denied the eternal and unchangeable Godhead in the essence of the Father, though he could not see it in the Unity of the Trinity. Macedonius was devoid of the light of the Truth when he did not receive the Godhead of the Holy Spirit, but he did acknowledge one power and the same nature in the Father and the Son. Sabellius was plunged into inextricable error by holding the unity of substance to be inseparable in the Father, Son and Holy Spirit, but granted to a singleness of nature what he should have attributed to an equality of nature , and because he could not understand a true Trinity, he believed in one and the same person under a threefold appellation. Photinus, misled by his mental blindness, acknowledged in Christ true man of our substance, but did not believe Him born God of God before all ages, and so losing the entirety of the Faith, believed the Son of God to have taken on Him the true nature of human flesh in such a way as to assert that there was no soul in it, because the Godhead Itself took its place. Thus, if all the errors which the catholic Faith has anathematized are recanted, something is found in one after another which can be separated from its damnable setting. But in the detestable dogma of the Manicheans there is absolutely nothing which can be adjudged tolerable in any degree.