On The Holy Trinity by St. Augustine
Begins by setting forth briefly and in sum the contents of the previous fourteen books. The argument is then shown to have reached so far as to allow of our now inquiring concerning the Trinity, which is God, in those eternal, incorporeal, and unchangeable things themselves, in the perfect contemplation of which a blessed life is promised to us. But this Trinity, as he shows, is here seen by us as by a mirror and in an enigma, in that it is seen by means of the image of God, which we are, as in a likeness that is obscure and hard of discernment. In like manner, it is shown, that some kind of conjecture and explanation may be gathered respecting the generation of the divine Word, from the word of our own mind, but only with difficulty, on account of the exceeding disparity which is discernible between the two words; and, again, respecting the procession of the Holy Spirit, from the love that is joined thereto by the will.