The Lesser Key of Solomon, also known as the Clavicula Salomonis Regis or Lemegeton, is an anonymous grimoire (or spell book) on demonology. It was compiled in the mid-17th century, mostly from materials a couple of centuries older. It is divided into five books—the Ars Goetia, Ars Theurgia-Goetia, Ars Paulina, Ars Almadel, and Ars Notoria.

Ars Goetia

The most obvious source for the Ars Goetia is Johann Weyer's Pseudomonarchia Daemonum in his De praestigiis daemonum. Weyer does not cite, and is unaware of, any other books in the Lemegeton, indicating that the Lemegeton was derived from his work, not the other way around. The order of the spirits was changed between the two, four additional spirits were added to the later work, and one spirit (Pruflas) was omitted. The omission of Pruflas, a mistake that also occurs in an edition of Pseudomonarchia Daemonum cited in Reginald Scot's The Discoverie of Witchcraft, indicates that the Ars Goetia could not have been compiled before 1570. Indeed, it appears that the Ars Goetia is more dependent upon Scot's translation of Weyer than Weyer's work in itself. Additionally, some material was used from Heinrich Cornelius Agrippa's Three Books of Occult Philosophy, the Heptameron by pseudo-Pietro d'Abano, and the Magical Calendar.