From the PREFACE: "Much has been written about the feats of miracle-mongers, and not a little in the way of explaining them. Chaucer was by no means the first to turn shrewd eyes upon wonder-workers and show the clay feet of these popular idols. And since his time innumerable marvels, held to be supernatural, have been exposed for the tricks they were. Yet to-day,if a mystifier lack the ingenuity to invent anew and startling stunt, he can safely fall back upon a trick that has been the favorite of press agents the world over in all ages. He can imitate the Hindoo fakir who, having thrown a rope high into the air, has a boy climb it until he is lost to view. He can even have the feat photographed. The camera will click; nothing will appear on the developed film; and this,the performer will glibly explain, ``proves''that the whole company of onlookers was hypnotized! And he can be certain of a very profitable following to defend and advertise him.