Liber Aleph vel CXI: The Book of Wisdom or Folly is the title of The Equinox, volume III, number VI, by Aleister Crowley.
The book consists of 208 short epistles on the philosophy of Thelema, Crowley's own ethical system of occult magic.
Even the titles of each epistle are given in Latin, and its often medieval guise of dealing with subject matters, such as the effects of "melancholy bile", can be considered another of Crowley's great examples of using ancient texts as templates.
The concept of the book is based on a passage from The Book of the Law (Liber AL vel Legis), the central text of Thelema, and states what appears to be a prophecy of later knowledge and secrets of the new Aeon of Horus being taught to a "magical son".
[2] The number 111 given to the title refers to the numerical value of the Hebrew letter Aleph spelt in full which in Hermetic teachings corresponds to the first Tarot trump The Fool.