60 Seeing, then, that the origin, the cause, the reason of so many and so important things, escapes you yourselves also, and that you can neither say nor explain what has been made, nor why and wherefore it should not have been otherwise, do you assail and attack our timidity, who confess that we do not know that which cannot be known, and who do not care to seek out and inquire into those things which it is quite clear cannot be understood, although human conjecture should extend and spread itself through a thousand hearts?
And therefore Christ the divine,— although you are unwilling to allow it—Christ the divine, I repeat, for this must be said often, that the ears of unbelievers may burst and be rent asunder, speaking in the form of man by command of the Supreme God, because He knew that men are naturally blind, and cannot grasp the truth at all, or regard as sure and certain what they might have persuaded themselves as to things set before their eyes, and do not hesitate, for the sake of their conjectures, to raise and bring up questions that cause much strife—bade us abandon and disregard all these things of which you speak, and not waste our thoughts upon things which have been removed far from our knowledge, but, as much as possible, seek the Lord of the universe with the whole mind and spirit; be raised above these subjects, and give over to Him our hearts, as yet hesitating whither to turn; be ever mindful of Him; and although no imagination can set Him forth as He is, yet form some faint conception of Him.
For Christ said that, of all who are comprehended in the vague notion of what is sacred and divine, He alone is beyond the reach of doubt, alone true, and one about whom only a raving and reckless madman can be in doubt; to know whom is enough, although you have learned nothing besides; and if by knowledge you have indeed been related to God, the head of the world, you have gained the true and most important knowledge.
Source: Against the Heathen (New Advent)