The so-called "barbarous names" refer to the often unintelligible corrupted Greek and Hebrew incantations appearing in many old magical grimoires, which purport to be the names of angels, spirits, and deities.

Many, including magician Aleister Crowley, believe that the names' lack of known meaning makes them more effective for magical purposes.

Related resources:

• Goetia
• Demonology
  Demonology, both ancient and modern, including the Goetia and other Demon-centered works, the legends of Solomon, fallen angels, and more.
• John Dee
  Historical Resources, Images, et al.
• Magick and Theory
  Magick and magickal theory. What Ritual magicians do, and why they do it. Essays on a number of subjects relating to Ritual/ Ceremonial Magick.
• Satanism
  Satanism as a religion and a philosophy. Every variety and type of Satanic belief, from the mythical Satanist of the Middle ages to modern ritual Satanists, Dabblers, and Gnostics.