During his disastrous naval assault on the city of Santa Cruz de Tenerife, Lord Nelson lost hundreds of men, and was driven from the coast in defeat. He was also shot in the arm, and had to have part of it amputated. This being 1797, the amputation was done by knife without anesthetic. He seems to have been a good sport about the accident, especially since, in a sense, he never lost the arm. For the rest of his life he could sense it, as though the appendage were extending invisibly from the stump. He supposedly claimed that he now knew there had to be an afterlife because if his arm could have a ghost, then so could he. Lord Nelson's arm is a particularly famous example of a phantom limb. Almost all people who have an amputation experience a phantom. Usually the effect fades within days, but in some cases it can remain for a lifetime. The reason for the phantom is both simple and profound. The brain constructs a model of the self that neuroscientists call the body schema. The body