Heinrich Cornelius Agrippa

Agrippa drafted De occulta philosophia in 1509-10, in his early twenties, and sent it to Trithemius for comment in April 1510. Trithemius praised it and told him to keep it quiet. He did, more or less, for two decades: the book circulated in manuscript and was not printed complete until 1533, at Cologne, in an edition that suppressed its printer and place because a Dominican inquisitor had denounced it while the type was still being set.

Its structure is the reason it mattered more than anything else in the field. Three books, ascending: natural magic, the virtues of stones, plants, animals and elements; celestial magic, the mathematical and astrological layer, numbers, seals and planetary hours; and ceremonial magic, the religious layer of divine names, angels and rites. Every correspondence table in Western magic since, Golden Dawn attributions, the planetary hours, the magic squares and planetary seals, the sigils of spirits, runs back to this book, usually through intermediaries who did not credit it.

The difficulty in reading him is that three years earlier he had published De incertitudine et vanitate scientiarum (Antwerp, 1530), a corrosive sceptical attack on the pretensions of every branch of learning, magic emphatically included, in which he disowns his own occult studies. Scholars have argued for four centuries about which Agrippa is the real one. The one fact that constrains the argument is chronological: he wrote the retraction first and shepherded the full magical encyclopedia into print afterwards, which is hard to reconcile with a straightforward conversion to scepticism. Christopher Lehrich's study treats the tension as deliberate rather than as a contradiction to be resolved.

He was a soldier, lawyer, physician, diplomat and perpetual debtor who quarrelled his way across Europe, and in 1519, as town advocate at Metz, he defended a woman accused of witchcraft and got her acquitted, attacking the inquisitor's reasoning and the Malleus it rested on. His student Johann Weyer carried that argument much further.

A Fourth Book of Occult Philosophy appeared in print in 1559, twenty-four years after Agrippa died, presenting itself as the practical completion of the three genuine books: the operative material, with the spirits, the seals and the actual procedure for conjuration.

It is spurious, and this was established immediately by the person best placed to know. Johann Weyer had been Agrippa's own student and lived in his household, and in De praestigiis daemonum (1563) he denounced the Fourth Book as a forgery falsely fathered on his master. That verdict has been challenged only occasionally since, Stephen Skinner has argued for some authentic material in it, and Thomas Willard has proposed Jacques Gohory as the actual author, and it stands.

This matters practically rather than pedantically. Later grimoire compilations, the Heptameron attributed to Peter of Abano and much of what descends into the Golden Dawn and modern ceremonial practice, draw on the pseudo-Agrippa alongside the real one, and the two are routinely cited together as though a single author had written both. A good deal of what is confidently attributed to Agrippa in occult writing comes from a book he did not write, published after his death, by someone using his name because it sold.