On The Holy Trinity by St. Augustine
Chapter 5.--Of Difficulties Concerning the Trinity: in What Manner Three are One God, and How, Working Indivisibly, They Yet Perform Some Things Severally.
8. Some persons, however, find a difficulty in this faith; when they hear that the Father is God, and the Son God, and the Holy Spirit God, and yet that this Trinity is not three Gods, but one God; and they ask how they are to understand this: especially when it is said that the Trinity works indivisibly in everything that God works, and yet that a certain voice of the Father spoke, which is not the voice of the Son; and that none except the Son was born in the flesh, and suffered, and rose again, and ascended into heaven; and that none except the Holy Spirit came in the form of a dove. They wish to understand how the Trinity uttered that voice which was only of the Father; and how the same Trinity created that flesh in which the Son only was born of the Virgin; and how the very same Trinity itself wrought that form of a dove, in which the Holy Spirit only appeared. Yet, otherwise, the Trinity does not work indivisibly, but the Father does some things, the Son other things, and the Holy Spirit yet others: or else, if they do some things together, some severally, then the Trinity is not indivisible. It is a difficulty, too, to them, in what manner the Holy Spirit is in the Trinity, whom neither the Father nor the Son, nor both, have begotten, although He is the Spirit both of the Father and of the Son. Since, then, men weary us with asking such questions, let us unfold to them, as we are able, whatever wisdom God's gift has bestowed upon our weakness on this subject; neither |let us go on our way with consuming envy.| Should we say that we are not accustomed to think about such things, it would not be true; yet if we acknowledge that such subjects commonly dwell in our thoughts, carried away as we are by the love of investigating the truth, then they require of us, by the law of charity, to make known to them what we have herein been able to find out. |Not as though I had already attained, either were already perfect| (for, if the Apostle Paul, how much more must I, who lie far beneath his feet, count myself not to have apprehended!); but, according to my measure, |if I forget those things that are behind, and reach forth unto those things which are before, and press towards the mark for the prize of the high calling,| I am requested to disclose so much of the road as I have already passed, and the point to which I have reached, whence the course yet remains to bring me to the end. And those make the request, whom a generous charity compels me to serve. Needs must too, and God will grant that, in supplying them with matter to read, I shall profit myself also; and that, in seeking to reply to their inquiries, I shall myself likewise find that for which I was inquiring. Accordingly I have undertaken the task, by the bidding and help of the Lord my God, not so much of discoursing with authority respecting things I know already, as of learning those things by piously discoursing of them.