Rivers of Empire: Water, Aridity, and the Growth of the American WestWhen Henry David Thoreau went for his daily walk, he would consult his instincts on which direction to follow. More often than not his inner compass pointed west or southwest. The future lies that way to me, he explained, and the earth seems more unexhausted and richer on that side. In his own imaginative way, Thoreau was imitating the countless young pioneers, prospectors, and entrepreneurs who were zealously following Horace Greeley's famous advice