One of the famous classical grimoires also known as the Greater Key of Solomon. In French it was available in the fourteenth century. A.E. Waite is willing to allow as much as two centuries before this time for the book to have been created and transmitted (perhaps orally), placing its true original as far back as the twelfth century. It would seem that scholars generally agree on the idea that the Key (along with the Lemegeton) is the fountainhead of Medieval grimoiric writing; providing the format, style, and even the content of those which followed.
The Key is composed of two books. Book one concerns the art of spirit summoning—without offering any set hierarchies of intelligences or the use of a triangle. Instead, the spirits arrive at the edge of the circle, and it is up to the mage to question them about their names and functions. Book two concerns itself with all ritual preparations—purifications, the construction of magickal tools, incense, holy water, etc. It is also the book from which Gerald Gardner drew much of his material in his formation of Wicca.