“Costly grace is the treasure hidden in the field; for the sake of it a man will gladly go  and sell all that he has. It is the pearl of great price for which the merchant will sell  all his goods. Costly grace is the gospel which must be sought again and again, the  gift which must be asked for, the door at which a man must knock. It is costly because
it costs a man his life, and it is grace because it gives a man the only true life.”
~ Dietrich Bonhoeffer, The Cost of Discipleship