Nothing, it seems, will help you see through the vanity of materialism quite like a $4.1 billion fortune. A few summers ago, I was sitting alone in the baronial boardroom at Spendthrift, waiting to interview the farm's owner. It was a hot day, but here all was panelled cool, the venerable furnishings slumbering through the prosperous drone of a lawnmower. I was thinking about this apt conflation of heritage and modernity when startled by the entry of a tanned octogenarian whose casual apparel, in the round, must have cost rather...