Throughout history pain has been one of humankind's most constant, yet most unwelcome, companions. Almost from the time people learned to record their feelings, pain has been a prominent subject. The agony an ancient Babylonian princess experienced echoes through the ages from the cuneiform writing on the walls of her tomb: "Pain has seized my body. May God tear this pain out."2 And, as constant and persistent as pain itself have been the efforts of countless doctors to find something-anything-to prevent pain.

Surgery and the pain associated with it are as old, and even older, than civilization. Human remains dating to prehistoric times show evidence of limb amputation and even a primitive form of brain surgery. The Egyptians, Babylonians, and Assyrians left written and pictorial records of surgical operations. As knowledge of human anatomy progressed, more complex surgeries were practiced in India, China, Greece...