My sister Martha is three years older than I and has always been considerably smarter. This put me at a disadvantage. Teachers in school would compare my work to Martha's and wonder if I came from the same litter. When I was four or five and Martha was seven or eight, she sometimes took advantage of my financial ignorance. I would have a dime and she would have a nickel. Showing me that the nickel was clearly larger than the dime, she would suggest a trade. I would gladly do so, wondering how my sister could be so dumb as to make such an offer. Not all trades are fair. Some take advantage of the ignorant or uninformed. But occasionally one bumps into a trade that is so magnanimous, so caring, so loving that it rattles our selfish bones.

At the heart of the Gospel is a terrific trade, what…