"Magic is the pretended performance of those things which cannot be done. The success of a magician's simulation of doing the impossible depends upon misleading the minds of his audiences. This, in the main, is done by adding, to a performance, details of which the spectators are unaware, and leaving out others which they believe you have not left out. In short a performance of magic is largely a demonstration of the universal reliability of certain facts of psychology." (John Mulholland, The Art of Illusion, Charles Scribner & Sons, 1944.)