Agrippa instructing his pupils in mathematics from the frontispiece of his "Treatise on the Science of Arms with Philosophical Dialogue," published in 1553. Heinrich Cornelius Agrippa von Nettesheim (1486-1535) was a German magician, occult writer, theologian, astrologer and alchemist. In 1510, he studied briefly with Johannes Trithemius, and Agrippa sent him an early draft of his masterpiece, De occulta philosophia libri tres; a study of elemental, celestial, and intellectual magic. The book discusses the four classical elements, (earth, air, fire, and water), astrology, numbers, angels, gods, mystical names and virtues, and how they relate to medicine and alchemy. During his wandering life in Germany, France and Italy he worked as a theologian, physician, legal expert and soldier. After Agrippa's death in 1535, rumors circulated about him summoning demons and that on his deathbed he released a black dog which had been his familiar.