Cross reference
Proverbs 20:5
5 Counsel in the heart of man is `like' deep water; But a man of understanding will draw it out.
Proverbs 18:4
4 The words of a man's mouth are `as' deep waters; The wellspring of wisdom is `as' a flowing brook.
Psalms 64:6
6 They search out iniquities; We have accomplished, `say they', a diligent search: And the inward thought and the heart of every one is deep.
1 Corinthians 2:11
11 For who among men knoweth the things of a man, save the spirit of the man, which is in him? even so the things of God none knoweth, save the Spirit of God.