Feast of St Ambrose
NOW, WE both know and confess that God is without beginning and without end, everlasting and eternal, uncreated, unchangeable, inalterable, simple, uncompounded, incorporeal, invisible, impalpable, uncircumscribed, unlimited, incomprehensible, uncontained, unfathomable, good, just, the maker of all created things, all-powerful, all-ruling, all-seeing, the provider, the sovereign, and the judge of all. We furthermore know and confess that God is one, that is to say, one substance, and that He is both understood to be and is in three Persons—I mean the Father and the Son and the Holy Spirit—and that the Father and the Son and the Holy Spirit are one in all things save in the being unbegotten, the being begotten, and the procession. We also know and confess that for our salvation the Word of God through the bowels of His mercy, by the good pleasure of the Father and with the co-operation of the All-Holy Spirit, was conceived without seed and chastely begotten of the holy Virgin and Mother of God, Mary, by the Holy Spirit and of her became perfect man; and that He is perfect God and at the same time perfect man, being of two natures, the divinity and the humanity, and in two intellectual natures endowed with will and operation and liberty—or, to put it simply, perfect in accordance with the definition and principle befitting each, the divinity, I mean, and the humanity, but with one compound hypostasis. And we know and confess that He hungered and thirsted and was weary, and that He was crucified, and that for three days He suffered death and the tomb, and that He returned into heaven whence He had come to us and whence He will come back to us at a later time. To all this holy Scripture and all the company of the saints bear witness.
But what the substance of God is, or how it is in all things, or how the only-begotten Son, who was God, emptied Himself out and became man from a virgin’s blood, being formed by another law that transcended nature, or how He walked dry-shod upon the waters, we neither understand nor can say. And so it is impossible either to say or fully to understand anything about God beyond what has been divinely proclaimed to us, whether told or revealed, by the sacred declarations of the Old and New Testaments.
—St John of Damascus, An Exact Exposition of the Orthodox Faith