Trithemius is best known for his hidden writing- the infamous Steganographia, but his other works, including this short grimoire on the use of crystals in summoning celestial spirits, are no less potent.Through the use of a simple wand, pedestal, lamen, and a polished and clear crystal, Trithemius states that it is possible to manifest and converse with celestial forces and to constrain them through the use of simple invocation and prayer.