EXPOSÉ OF ONE OF THE FIRST GREAT CONJURORS FIRST EDITION, [4], XVI, 138, [2]pp., copper engraved frontispiece by Antoine Frençois Hémery showing a card trick,, engraved title, slight marginal trimming not affecting border, wood engraved head pieces throughout, final leaf repaired, later half vellum over 19th century marbled boards, original red morocco label to spine, 8vo, Paris, Chez Langlois libraire, rue du Petit Pont, 1784 First Edition of Decremps’ first work on the inner workings of stage magic. Decremps was the first to demystify the scammer by explaining all his experiments (card tricks, cups and game bags, etc.) and listed the cheating techniques, such as false shuffling, cutting jumps, second dealing, etc. Jurist and diplomat, Henri Decremps (1746-1826) served as the Secretary to the French Embassy in London, before returning to Paris in 1783. He studied Western esotericism and stage magic, developing skills that he used to write his book, published a year later in 1784. La Magie blanche dévoilée (White Magic Revealed) was immediately successful and was translated into English. It explained how the state magicians produced their tricks, intended to unmask charlatans and crooks, including the most famous of them, Joseph Pinetti, purported physicist and magician of the court of Louis XVI.  La Magie Blanche appeared in Paris while Pinetti was still playing there in 1784, and he reacted by introducing in his shows an actor pretending to be Decremps, who tried without success to explain how the tricks worked. Incited by Pinetti, the audience would then throw the actor out of the theatre. Decremps responded by writing four more books denouncing Pinetti as a charlatan pretending to have supernatural powers. Decremps works did have a devastating effect on Pinetti as well as on other practitioners of mystic art, despite the fact that Decremp's explanations were largely guesswork.  Decremps would later become an enthusiastic supporter of the French Revolution.  [Hall, Old Conjuring Books, p. 156-158, 174; Ruegg, Bibliography of French prestidigitation, p. 31-32, D. Price. Magic, 1985, p. 40]