The Grand Grimore, authored by Reuben Swinburne Clymer under the pseudonym "Pythagoras 38," is an eclectic occult training manual intended for lodge members. (It is crucial not to confuse this work with the medieval Grand Grimoire.)

This unique occult volume, published in 1910, incorporates material from various classic grimoires, magical evocation rituals, and other occult practices, such as instructions on using the planchette, imagination magic, and breathing exercises.

The Grand Grimore holds a special place in Americana literature, as it emerged during a significant period in American history when the occult movement experienced a surge, primarily influenced by the groundwork laid by Paschal Beverly Randolph. This movement found its foothold in Masonic and new Rosicrucian organizations, shaping a new occult movement in 20th-century America.

This revised edition includes numerous magical sigils and rituals, along with a special Post Scriptum providing valuable information about the author Reuben Swinburne Clymer and the historical context surrounding the publication of The Grand Grimore.