Psalm 92:6 (NIV) The senseless man does not know, fools do not understand,
Romans 3:11 (NIV) There is no one who understands, no one who seeks God.
John 14:9 (NIV) Jesus answered: "Don't you know me, Philip, even after I have been among you such a long time? Anyone who has seen me has seen the Father. How can you say, 'Show us the Father'?"
Since it is God we are speaking of, you do not understand it. If you could understand it, it would not be God. —Augustine
Sermons, in Christianity Today, "Reflections," Vol. 44, no. 9., Today's Best Illustrations – Volume 5, (Carol Stream, IL: Christianity Today, 1997), WORDsearch CROSS e-book, Under: "UNDERSTANDING".