On The Holy Trinity by St. Augustine
Chapter 13.--How the Word Beginning (Principium) is Spoken Relatively in the Trinity.
14. The Father is called so, therefore, relatively, and He is also relatively said to be the Beginning, and whatever else there may be of the kind; but He is called the Father in relation to the Son, the Beginning in relation to all things, which are from Him. So the Son is relatively so called; He is called also relatively the Word and the Image. And in all these appellations He is referred to the Father, but the Father is called by none of them. And the Son is also called the Beginning; for when it was said to Him, |Who art Thou?| He replied, |Even the Beginning, who also speak to you.| But is He, pray, the Beginning of the Father? For He intended to show Himself to be the Creator when He said that He was the Beginning, as the Father also is the beginning of the creature in that all things are from Him. For creator, too, is spoken relatively to creature, as master to servant. And so when we say, both that the Father is the Beginning, and that the Son is the Beginning, we do not speak of two beginnings of the creature; since both the Father and the Son together is one beginning in respect to the creature, as one Creator, as one God. But if whatever remains within itself and produces or works anything is a beginning to that thing which it produces or works; then we cannot deny that the Holy Spirit also is rightly called the Beginning, since we do not separate Him from the appellation of Creator: and it is written of Him that He works; and assuredly, in working, He remains within Himself; for He Himself is not changed and turned into any of the things which He works. And see what it is that He works: |But the manifestation of the Spirit,| he says, |is given to every man to profit withal. For to one is given by the Spirit the word of wisdom; to another the word of knowledge by the same Spirit; to another faith by the same Spirit; to another the gifts of healing by the same Spirit; to another the working of miracles; to another prophecy; to another the discerning of spirits; to another divers kinds of tongues; to another the interpretation of tongues: but all these worketh that one and the self-same Spirit, dividing to every man severally as He will;| certainly as God -- for who can work such great things but God? -- but |it is the same God which worketh all in all.| For if we are asked point by point concerning the Holy Spirit, we answer most truly that He is God; and with the Father and the Son together He is one God. Therefore, God is spoken of as one Beginning in respect to the creature, not as two or three beginnings.