John Hull lost his sight more than 20 years ago. He has written extensively about the nature of blindness. In the course of this, he has developed a philosophy of disability or impairment which emphasises the many different worlds of human experience. This leads him to the thought that the teacher of special children, many of whom will be living in or on the fringes of one of these worlds, must be able to enter imaginatively into other human worlds and thus become a trans-world educator.