Cross reference
Proverbs 20:5
5 The purpose in the heart of a man is like deep water, but a man of good sense will get it out.
Proverbs 18:4
4 The words of a man's mouth are like deep waters: the fountain of wisdom is like a flowing stream.
Psalms 64:6
6 Or make discovery of our secret purpose? The design is framed with care; and the inner thought of a man, and his heart, is deep.
1 Corinthians 2:11
11 For who has knowledge of the things of a man but the spirit of the man which is in him? in the same way, no one has knowledge of the things of God but the Spirit of God.