From Atlas Obscura:
There is an anonymous-looking office building located in Midtown Manhattan that hides a secret library for magicians.
It sounds fantastical enough to have been created by Terry Pratchett or J.K. Rowling, but the Conjuring Arts Research Center is very much real, and one of the world’s greatest collections of books dedicated to the deceptive arts.
. . . .
Conjuring Arts may be hard to find, but it is located in the heart of New York’s magic community. A few blocks northeast is Tannen’s, the oldest operating magic shop in the city, and a few blocks to the west is Fantasma, a magic store home to the largest Houdini museum in the world. One of the people on the Center’s Board of Directors is Brooklyn-born magician David Blaine.
The not-for-profit organization was established in 2003, “dedicated to the preservation and interpretation of magic and its allied arts.” It was started by William Kalush, who developed a love of magic from the card tricks shown to him by his father, a Marine wounded in World War II. This love of card magic turned to a love of collecting magic books, which now form a wondrous collection of over 15,000 books—some dating to over 600 years old—housed in this hidden location.
. . . .
Browsing through the shelves stacked with all things conjuring, you will find obscure books on sleight-of-hand techniques, mentalism, deceptive gambling, the history of magic, and the mysterious secrets of card tricks. One book is the seminal The Expert At the Card Table, which appeared in 1902, written by an S. W. Erdnase. It’s one of the most detailed collections of sleight-of-hand techniques and card sharping, a book so iconic and well-studied within magic circles it is known as “the Bible.” Appropriately enough, S. W. Erdnase was a pseudonym. The real identity of the writer has remained a century-old mystery.
. . . .
It is in the center of the library, in a windowless room under lock and key, that lies the true treasure of this remarkable place; the rare-book room. Within are shelves full of ancient European texts bound in vellum, with mysterious-sounding names such as Onomatalog Cvriosa et Magica. These incredibly rare books contain the early written history of magic. “Many are unique and can’t be found anywhere else in the world,” says Kalush, holding a book written in Florence in 1491 that promised to show how to read people’s minds.
Link to the rest at Atlas Obscura
Deep in the stacks is where a publisher found the real magic of making money with ‘whale math(TM)’ and shared it with only their closest of friends.
One of the secrets was the use of a paid ‘decoy’ to hide the magicians’ tricks, and thus became the ‘agent’ – one appearing to be a champion of the author – but far too often secretly a lapdog of the publisher.