The Bible speaks of hearts of stone and flesh:
Ezekiel 36:26 (NIV)
I will give you a new heart and put a new spirit in you; I will remove from you your heart of stone and give you a heart of flesh.
Your heart pumps life-sustaining blood to every cell in your body. The stonier your heart, the weaker the pump, the less life to the cells. You starve, cell by cell.
Every time I harden my heart, O God, I cut off your life-flow. I don’t want to suffocate slowly. I want to live abundantly! Give me a heart of flesh.
Never been said that I have a stony heart…but rocks in my head, that’s another matter.
Your head–a rock of strength, I’d say.