This book has been written in the endeavour to meet a want which has often been pointed. Out to me. Within its pages I have tried to give a simple account of the nature and effects of hypnotism — to show how the state is produced, and what it is. It is not, perhaps, the easiest thing in the world for a writer, on such a subject, to treat his theme popularly, and, at the same time, scientifically; and I am conscious of very many faults. The use of technical terms has been avoided, and controversial questions have not been much discussed, as this would have led me too far from my original purpose.