“Sir Arthur, I have devoted a lot of time and thought to this illusion ... I won’t tell you how it was done, but I can assure you it was pure trickery. I did it by perfectly normal means. I devised it to show you what can be done along these lines. Now, I beg of you, Sir Arthur, do not jump to the conclusion that certain things you see are necessarily “supernatural,” or the work of “spirits,” just because you cannot explain them....”