On Philip Yancey’s website he tells of being asked to define what grace is. This is his illuminating response,
I don’t even try. Jesus talked a lot about grace, but mainly through stories. I remember once getting stuck in Los Angeles traffic and arriving 58 minutes late at the Hertz rental desk. I walked up in kind of a bad mood, put the keys down and said, “How much do I owe?” The woman says, “Nothing. You’re all clear.” I said I was late and she smiled, “Yes, but there’s a one-hour grace period.” So I asked, “Oh really, what is grace?” And she said, “I don’t know. [They must not cover that in Hertz training classes.] I guess what it means is that even though you’re supposed to pay, you don’t have to.” That’s a good start to a definition.