Augustine, Echoing the Nicene Creed (w/Filioque)

“We believe, hold, and faithfully proclaim that the Father has begotten the Word: that is, the Wisdom by which all things have been made, his only-begotten Son, one begotten of one, eternal of eternal, Supreme Good of Supreme Good. And we believe that the Holy Spirit is at the same time the spirit of the Father and of the Son, himself consubstantial and co-eternal with both, and that this totality is a Trinity in respect of the distinctive character of the persons, and is also one God in respect of the inseparable divinity, just as it is one Omnipotent in respect of the inseparable omnipotence; but with this provision, that when the question is asked about each individual [person] the reply is that each is God and Omnipotent, whereas when the question is about all at the same time, they are not three Gods or three Omnipotents, but one God omnipotent. Such is the inseparable unity in persons; and this is how that Unity wills to be proclaimed.” [City of God: Book XI, Chapter 24.]