10 We, however, who propose to discourse of that most perfect majesty and fullest Divinity which appertains to the Only-begotten Son of God, have no fear lest our readers should imagine that amplitude of phrase in speaking of the Son is a detraction from the glory of God the Father, as though every praise assigned to the Son had first been withdrawn from Him. For, on the contrary, the majesty of the Son is glory to the Father; the Source must be glorious from which He Who is worthy of such glory comes. The Son has nothing but by virtue of His birth; the Father shares all veneration received by that birthright. Thus the suggestion that we diminish the Father's honour is put to silence, for all the glory which, as we shall teach, is inherent in the Son will be reflected back, to the increased glory of Him who has begotten a Son so great.
Source: On the Trinity (New Advent)