He is Baptized at Milan with Alypius and His Son Adeodatus. The Book De Magistro
14 Thence, when the time had arrived at which I was to give in my name, having left the country, we returned to Milan. Alypius also was pleased to be born again with me in You, being now clothed with the humility appropriate to Your sacraments, and being so brave a tamer of the body, as with unusual fortitude to tread the frozen soil of Italy with his naked feet. We took into our company the boy Adeodatus, born of me carnally, of my sin. Well had Thou made him. He was barely fifteen years, yet in wit excelled many grave and learned men. I confess unto You Your gifts, O Lord my God, Creator of all, and of exceeding power to reform our deformities; for of me was there naught in that boy but the sin.
For that we fostered him in Your discipline, You inspired us, none other—Your gifts I confess unto You. There is a book of ours, which is entitled The Master. It is a dialogue between him and me. You know that all things there put into the mouth of the person in argument with me were his thoughts in his sixteenth year. Many others more wonderful did I find in him. That talent was a source of awe to me. And who but Thou could be the worker of such marvels? Quickly did You remove his life from the earth; and now I recall him to mind with a sense of security, in that I fear nothing for his childhood or youth, or for his whole self.
We took him coeval with us in Your grace, to be educated in Your discipline; and we were baptized, and solicitude about our past life left us. Nor was I satiated in those days with the wondrous sweetness of considering the depth of Your counsels concerning the salvation of the human race. How greatly did I weep in Your hymns and canticles, deeply moved by the voices of Your sweet-speaking Church! The voices flowed into mine ears, and the truth was poured forth into my heart, whence the agitation of my piety overflowed, and my tears ran over, and blessed was I therein.
Source: Confessions (New Advent)