Green is the color of vegetation, in particular of healthy, growing leaves. At least in the growing season it is the predominant color of undeveloped land in non-polar, non-arid regions. Green as a quality of the landscape was what was destroyed or threatened by the Industrial Revolution in Britain. Thus William Blake, in the poem that has become the hymn Jerusalem, contrasted the green and pleasant land that England should be with the dark satanic mills of his time (early-nineteenth century). And Richard Llewellyn's 1939 novel How Green Was My Valley tells the heartbreaking story of the gradual transformation of a rural landscape, where young boys caught trout in the river, to a polluted industrial wasteland where the wastes from coal mining, dumped on the sides of the narrow South Wales valley, threatened to engulf the miners' houses.

Green as undeveloped land, free from industry, is what...