On The Holy Trinity by St. Augustine
Chapter 8.--The Entire Trinity Invisible.
14. Let us therefore say nothing of those who, with an over carnal mind, have thought the nature of the Word of God, and the Wisdom, which, |remaining in herself, maketh all things new,| whom we call the only Son of God, not only to be changeable, but also to be visible. For these, with more audacity than religion, bring a very dull heart to the inquiry into divine things. For whereas the soul is a spiritual substance, and whereas itself also was made, yet could not be made by any other than by Him by whom all things were made, and without whom nothing is made, it, although changeable, is yet not visible; and this they have believed to be the case with the Word Himself and with the Wisdom of God itself, by which the soul was made; whereas this Wisdom is not only invisible, as the soul also is, but likewise unchangeable, which the soul is not. It is in truth the same unchangeableness in it, which is referred to when it was said, |Remaining in herself she maketh all things new.| Yet these people, endeavoring, as it were, to prop up their error in its fall by testimonies of the divine Scriptures, adduce the words of the Apostle Paul; and take that, which is said of the one only God, in whom the Trinity itself is understood, to be said only of the Father, and neither of the Son nor of the Holy Spirit: |Now unto the King eternal, immortal, invisible, the only wise God, be honor and glory for ever and ever;| and that other passage, |The blessed and only Potentate, the King of kings, and Lord of lords; who only hath immortality, dwelling in the light which no man can approach unto; whom no man hath seen, nor can see.| How these passages are to be understood, I think we have already discoursed sufficiently.