A heart of stone is hardened, cold, frozen, stopped, immovable, unfeeling, uncaring, guarded, & numb.
A heart of flesh is soft, malleable, pulsing, enlivening, thriving, growing, connecting, vulnerable, & feeling.
Ezekiel 36:26 - " 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."
Song Reference: Midnight Blue, Lou Gramm, 1987