HERE IS a true story about a piece of ground on Long Island. It had a lawn on it and was doing fine. One day a contractor decided to put up some houses nearby. Bulldozers rushed in and reshaped the plot: it used to be flat; now it was sloped. The contractor's men planted a new lawn and went away, but the ground was no longer in a position to support a lawn in the style to which lawns are accustomed. After every rain, the runoff from surrounding lots would carve a deep gully down its center. Then the contractor's...