"Many," Lavers remarks, "have tried to track the unicorn's progress and a few have glimpsed madness along the way." His own aim, he states, is not to attempt a complete history, merely to "say a few things about the unicorn that have not been said before ... and to draw attention to the myth's natural history." The story begins in 398 BC when Ctesias of Cnidus, a Greek physician to the king of Persia, gave an account of "certain wild asses" native to India, with white bodies, red heads, dark blue eyes and a single 18-inch horn, nattily striped in red, black and white. They ran fast and tasted terrible. From this exotic fragment, Lavers embarks on a painstaking matching exercise, considering the possible candidates — rhinoceros, walrus, deer with very long horns standing sideways on a mountain-top a vast distance away from its human observer, and so on.