8 And therefore, although in the two last books I have proved from the teaching of the Law and Prophets that God and God, true God and true God, true God the Father and true God the Son, must be confessed as One true God, by unity of nature and not by confusion of Persons, yet, for the complete presentation of the faith, I must also adduce the teaching of the Evangelists and Apostles. I must show from them that true God, the Son of God, is not of a different, an alien nature from that of the Father, but possesses the same Divinity while having a distinct existence through a true birth.
And, indeed, I cannot think that any soul exists so witless as to fancy that, although we know God's self-revelations, yet we cannot understand them; that, if they can be understood, would not wish to understand, or would dream that human reason can devise improvements upon them. But before I begin to discuss the facts contained in these saving mysteries, I must first humble the pride with which these heretics rebuke the names of other heresies. I shall hold up to the light this ingenious cloak for their own impiety. I shall show that this very means of concealing the deadliness of their teaching serves rather to reveal and betray it, and is a widely effectual warning of the true character of this honeyed poison.
Source: On the Trinity (New Advent)