The so-called Fourth Book: an apocryphon under Agrippa's name

Agrippa died around 1535, at Grenoble. About a quarter of a century later a book began to circulate in print bearing his name and presenting itself as the continuation of the De occulta philosophia: the Liber quartus de occulta philosophia, seu de cerimoniis magicis. The title promised what the three authentic books had left in shadow, namely the practical part of ceremonial magic. From the start, however, its authenticity was contested by those who had known Agrippa well.

The appearance of the text

The first edition of the Fourth Book is commonly dated to 1559 and placed at Marburg, although the bibliography of these printings is complex. The text is short and very different in tone from the three books of 1533: it lacks the ample quotations of philosophers and theologians, offering instead concise descriptions of names, characters and ceremonies. Many scholars regard it as an anonymous compilation, made by exploiting Agrippa's fame to lend authority to material of other origins.

In later editions the Fourth Book was often printed together with other magical texts, such as the Heptameron attributed to the Paduan physician Pietro d'Abano, who died in the early fourteenth century, and the Isagoge of Georg Pictorius. These miscellaneous volumes, reprinted several times, helped spread the idea that there existed a genuine Agrippan corpus devoted to evocations.

Johann Weyer's denial

The most important testimony against its authenticity comes from Johann Weyer, a Dutch physician who in his youth had been Agrippa's pupil and assistant. In De praestigiis daemonum, published at Basel in 1563, Weyer declared that the Fourth Book was not the work of his master. His treatise is remembered for another reason too: it argued that many women accused of witchcraft were ill or victims of illusions, not accomplices of the devil.

Weyer's testimony carries considerable weight, because it comes from a man who had lived alongside Agrippa and knew his papers. Modern historians largely agree with him: the style, the contents and the circumstances of publication make it very unlikely that the text is by Agrippa. For scholarship the question can be considered essentially settled, although the text continues to be reprinted under his name.

The black legend

The Fourth Book fed a reputation that Agrippa already had in his lifetime. The historian Paolo Giovio, in his Elogia, related that the black dog that accompanied him was in reality a demon, which at its master's death threw itself into the river. Weyer denied this rumour too, explaining that it was an ordinary dog named Monsieur, of which Agrippa was very fond.

The legend survived nonetheless. Christopher Marlowe, in Doctor Faustus, has his protagonist wish to be «as cunning as Agrippa was». The English translation of the Fourth Book, published by Robert Turner in 1655, prolonged its fortune. In 1818, in Mary Shelley's Frankenstein, the young Victor reads none other than Cornelius Agrippa, by then a symbol of forbidden knowledge.

The story of the Fourth Book shows how an author's fame can be built even by texts he did not write. The real Agrippa, an erudite and restless philosopher, was long overshadowed by the legendary magician created by false attributions and rumours. Distinguishing the three authentic books from the apocryphon is the first step towards reading him as an author of the Renaissance.