When it comes to magic tricks, there are a number of tricks up the proverbial sleeve of a magician: card tricks, disappearing tricks, and a “book test.” You may not know a book test by its name, but rest assured, if you have ever seen a magician perform magic tricks, then this is a popular go-to trick. It gives the illusion that the magician is a mentalist or mind reader.
What Is It?
In the classic example of a book test, you or another spectator may be asked turn to any page in a large book (like a dictionary or encyclopedia) and select a word or sentence. The passage may be revealed to the audience or recorded in some other way for later comparison.
In this trick, the magician is supposed to “telepathically” name the word or offer an impression of what is in the sentence. In some scenarios of the trick, the magician might even know the page number. The premise of the trick is that there may be thousands of words in a book, yet the magician is able to somehow identify the one word, sentence, or image within the book.
Book tests come in different forms. Some are based on real, ungimmicked books, and others are based on gaffed ones.
Yesterday and Today
Magicians have been using books as props for magic tricks dating as far back as the 1400s. A version of a book test was created by well-known publisher Girolamo Scotto for the Emperor of Austria in 1572. Although this book test no longer exists, it was well known and the talk of the town at the time.
Italian magician Vanni Bossi created “The Labyrinth” book test in 1607, which still survives today. It had been reproduced in English in 1610 and spurred many variations for hundreds of years afterward.
Popular modern-day book tests include Double Coincidence by magician Devin Knight, the Houdini Book Test, not actually by Houdini but by Black’s Magic Group, and the “Taylor Made Book Test” by magician David Taylor.
Although Harry Houdini was the world's most famous trickster, he was also skeptical of "supernatural powers." He used to visit seances in disguise to expose their leaders as frauds.
The Many Ways It's Done
In some cases, the magician is able to derive the correct answer through basic mathematics. For example, the magician may first ask an unwitting person to choose a word or figure on a starting page. From there, that word, passage, or image leads to another predestined page, and then this pattern continues a few times, all leading the unsuspecting person down a predetermined path. After three flips, the magician stops the person and reveals the word, sentence, or figure.
Another way a magician is guaranteed to “guess” it right is by using a modified or gimmicked book. In these cases, the magician needs to memorize key things on the gimmicked book’s page to know what a person may pick. Or, using sleight of hand, the magician can incidentally insert a gimmicked page into a “natural” book, which is a book that is completely undoctored with the exception of the insertion of the gimmick page.
In another version of the trick, a natural book may also be used, like a dictionary, but the magician guides the person to pick something specific. Then, the magician may lightly pencil in the answers on another part of the page when the person is redirected to look elsewhere.
Other variations, such as involving three or more people, can be pretty easy. In this case, the unsuspecting people use envelopes to record their answers. The trick is for the magician to ask the person to write down their answer and put it in an envelope. Then, the next person is asked to imagine opening the book to a random page and write down the page, line, and word they imagined (the person will be guided to what the first person selected). With sleight of hand, the magician palms the writer’s actual slip and hands the next reader a prepared slip, who opens the book to a selected section. Then, the third person (who does not select anything) just opens the prepared envelope to reveal the same word, sentence, or image.