A variety of factors contribute to our not being aware of the sacred, of God, as the encompassing reality all around us. The Bible uses several metaphors to image the resulting human condition. One of its central metaphors is that we have "hard hearts." To understand the metaphor, we need to know that the "heart" in the biblical tradition is an image for the self at the deepest level. . . .
What matters is the condition of the heart. One can have a "hard heart" or a "soft heart." Each is part of a family of metaphors. A "hard heart" is also "a heart made of stone," a heart that is "closed" and "shut," "a fat heart" enclosed in a thick layer, a heart that is "proud" and puffed up. Or one can have "a soft heart," "a tender heart," "a heart made of flesh," "a broken heart."
— Marcus J. Borg, The God We Never Knew