Apart from his importance for 17th century Russian literature, Simeon Polockij was a learned man who assembled the largest private library in Moscow. His 600 books by mostly Catholic authors writing in Latin and Polish confirm the view that Simeon was a Trojan horse of Western learning in the largely conservative Orthodox milieu of Moscow. His collection is today preserved as part of the Synodal Press Library in the Russian State Archive of Ancient Documents. This book for the first time separates out Simeon's collection from the larger library and describes it. The alphabetical catalogue records publication details, collations, owner's inscriptions and editorial information.