Secret Heart?

After a grievous sin, David pours forth a song of repentance and penance. And he says something that makes me curious.....
Psalm 51:6 Behold, you delight in truth in the inward being, and you teach me wisdom in the secret heart.

Secret Heart?  What...?
The Amplified renders it 'inmost heart'.  King James - 'Hidden part'

The word actually means 'stopped up' or 'barricaded'
A Place where no one is allowed in or out....
That place I don't even know myself....

O God. 
Teach me Your wisdom, in that place in my heart.

O Yes Lord.

PJ