One of the most overlooked occult texts ever penned, the Philosophical Merlin purports to be a French grimoire, translated into English, originally used by Napolean Bonaparte and his troops for military success, but was actually of primordial British manufacture. Originally released in 1822, it saw limited success and was largely forgotten.
Its celestial and divinatory content, though, is not to be overlooked; had it been rediscovered in any great degree during the horoscope-and-crystal days of the 1960s in Haight Ashbury it would have become a cult success, with a simplistic system similar to I-Ching (and possibly based off the latter) used to draw a nativity for the reader, which allows them to inform their decisions and thoughts on a cosmic basis.
Once forgotten, it now returns to impart its wisdom on the world once more.