Max Lucado tells the following story:

A Chinese man named Li Fuyan had tried every treatment imaginable to ease his throbbing headaches. Nothing helped. An X-ray finally revealed the culprit. A rusty four-inch knife blade had been lodged in his skull for four years. In an attack by a robber, Fuyan had suffered lacerations on the right side of his jaw. He didn't know the blade had broken off inside his head. No wonder he suffered from such stabbing pain.

Lucado comments:

We can't live with foreign objects buried in our bodies. Or our souls. What would an X-ray of your interior reveal? Regrets over an [earlier] relationship? Remorse over a poor choice? Shame about the marriage that didn't work, the habit you couldn't quit, the temptation you didn't resist, or the courage you couldn't find? Guilt lies hidden beneath the surface, festering, irritating. Sometimes so deeply embedded you don't know the cause.