Augustine De lib. arb 2.2.6

Augustine: You remember aright. We cannot deny what we held even at the very beginning of Book 1: Believing is one thing, understanding another; we should first believe the great and divine matter that we desire to understand.25 Otherwise, the prophet’s words, “Unless you believe you shall not understand” [Is. 7:9], would be in vain. Our Lord Himself also encouraged belief in those whom He called to salvation with both His words and His deeds. But afterwards, when speaking about the gift He was going to give to those who believe, He did not say “This is life eternal, that they might believe…” but rather: “This is life eternal, that they might know you, the true God, and Jesus Christ, the one whom You have sent” [Jn. 17:3]. Then He said to those who already believed “Seek, and you shall find” [Mt. 7:7]. For something that is believed but not known cannot be said to be ‘found.’ Nor is anyone made suitable for the task of finding God unless he first believes what he will later know. Consequently, let us obey the Lord’s precepts in pressing our inquiry. What we seek with His encouragement we shall find when He Himself shows it to us – at least insofar as these things can be found in this life by people such as ourselves. For we must believe that better people – even some who dwell in this world, and certainly all good religious people in the afterlife – grasp and recognize these things more evidently and completely. We must hope that we are going to be so, desiring and taking delight in such things, disdaining worldly and human things completely