The Rosicrucian Liber M
“He finally settled down in the German-speaking world where he founded a brotherhood called the Fraternity of the Rosy Cross, centered around a building called Sancti Spiritus. Originally the fraternity consisted of four members, but the number increased gradually. Central to their study was a certain “magical language and writing, with a large dictionary, which we yet daily use to God’s praise and glory, and do find great wisdom therein.” There was also a mysterious book called Liber M, which C. R. had translated and brought with him from Damascus. This book Paracelsus had—according to the Fama—studied “diligently,” although not being a member of the fraternity.”
–Henrik Bogdan, Western Esotericism and Rituals of Initiation, 2007, pg. 63.