De Occulta Philosophia Libri Tres, Three Books of Occult Philosophy, (1531-3)
The Three Books of Occult Philosophy was written by famous German magician, astrologer, and alchemist Heinrich Cornelius Agrippa. The books dealt with Elemental, Celestial, and Intellectual magic and proposed that magic was real, and it could be studied and used by devout Christians, as it was derived from God, not the Devil.
These three kinds of magic are subdivided into many other different disciplines that include the four elements, astrology, Kabbalhaism, numerology, angelology, scrying, and alchemy.
Though lacking the practical instruction of many grimoires, Agrippa’s work was used as a manual for magical practices.