One afternoon in the spring of 1877 a solitary horseman rode down the long, ghastly desert slant toward the ford at Green River.He was a young man in years, but he had the hard face and eagle eye of one matured in experience of that wild country. He bestrode a superb bay horse, dusty and travel-worn and a little lame. The rider was no light burden, judging from his height and wide shoulders; moreover, the saddle carried a canteen, a rifle, and a pack. From time to time he looked back over his shoulder at the magnificent, long cliff wall, which resembled a row of colossal books with leaves partly open. It was the steady, watchful gaze of a man who had left events behind him.