At the end of the book On the Trinity St. Augustine prays to God for grace to know Him and make Him known. Relentlessly pursuing God but also recognizing the limitations of his own intellect, he humbly relies on God to lead him into the truth. His prayer expresses the fervency and humility that should be in the heart of every follower of Jesus Christ, especially those who have been appointed to teach and preach within the Body of Christ.
Directing my purpose by this rule of faith, so far as I have been able, so far as Thou hast made me to be able, I have sought Thee, and have desired to see with my understanding what I believed; and I have argued and labored much. O Lord my God, my one hope, hearken to me, lest through weariness I be unwilling to seek Thee, but that I may always ardently seek Thy face.Do Thou give strength to seek, who hast made me find Thee, and hast given the hope of finding Thee more and more. My strength and my infirmity are in Thy sight: preserve the one, and heal the other.My knowledge and my ignorance are in Thy sight; where Thou hast opened to me, receive me as I enter; where Thou hast closed, open to me as I knock. May I remember Thee, understand Thee, love Thee. Increase these things in me, until Thou renewest me wholly.
You can read the rest of his prayer, as well as the rest of the book, here.