New Delhi, July 19 -- "I have fun like a child in the street. When the day comes when I'm not enjoying it, I will leave football." - Lionel Messi

Lionel Messi did not say this to be charming. He said it because it is the truest thing he knows about himself. It is the one condition he has always placed on his own continuation.

He has not anchored it to trophies, contracts, or records. He has anchored it to joy, the simplest and most uncorruptible measure there is. And today, on the eve of a World Cup final against Spain, that line carries more weight than it ever has before.

The quote draws its power from its central image. Messi does not describe himself as a professional or an athlete. He describes himself as a child in the street. He...