For more than a quarter of a century, Ildefonso, a Mexican Indian, lived in total isolation, set apart from the rest of the world. He wasn't a political prisoner or a social recluse, he was simply born deaf and had never been taught even the most basic language. Susan Schaller, then a twenty-four-year-old graduate student, encountered him in a class for the deaf where she had been sent as an interpreter and where he sat isolated, since he knew no sign language. She found him obviously...