The Spurious Sequel

The so-called Fourth Book of Occult Philosophy is a practical supplement falsely attributed to Agrippa and first printed some decades after his death (from about the 1550s). Where Agrippa's genuine three books are largely theoretical, the Fourth Book is operational, giving concrete instructions for making spirits appear, consecrating tools, and the natures of angelic and infernal spirits, and it is usually printed together with several other short practical texts, the Heptameron ascribed to Peter of Abano, the Isagoge of Georg Pictorius, and treatises on geomancy and the notory art.

Agrippa's own pupil Johann Weyer flatly denied that his master wrote it, and modern scholarship agrees: it is pseudo-Agrippa, trading on the fame of the Occulta philosophia to lend authority to a body of conjuring material Agrippa himself had treated more cautiously. Its interest is as evidence of how quickly, and how profitably, a famous magical author's name could be borrowed to authorise texts he had nothing to do with, a pattern pervasive in the grimoire tradition.