38 And therefore we look to Your support for the first trembling steps of this undertaking, to Your aid that it may gain strength and prosper. We look to You to give us the fellowship of that Spirit Who guided the Prophets and the Apostles, that we may take their words in the sense in which they spoke and assign its right shade of meaning to every utterance. For we shall speak of things which they preached in a mystery; of You, O God Eternal, Father of the Eternal and Only-begotten God, Who alone art without birth, and of the One Lord Jesus Christ, born of You from everlasting.
We may not sever Him from You, or make Him one of a plurality of Gods, on any plea of difference of nature. We may not say that He is not begotten of You, because You are One. We must not fail to confess Him as true God, seeing that He is born of You, true God, His Father. Grant us, therefore, precision of language, soundness of argument, grace of style, loyalty to truth. Enable us to utter the things that we believe, that so we may confess, as Prophets and Apostles have taught us, You, One God our Father, and One Lord Jesus Christ, and put to silence the gainsaying of heretics, proclaiming You as God, yet not solitary, and Him as God, in no unreal sense.
Source: On the Trinity (New Advent)