Meyah – gut (מעה) The translation "heart" in Psalm 40:8 "your Torah is within my heart" is not actually lev (לב), the correct Hebrew word. David actually said, "your torah is within my meyah - guts. He was so excited about God's word that it moved his guts, his very  being. Interestingly, in Hebraic thought, the mind is in the heart, not the brain.