The Imagined Library Books that were never written

The Cthulhu Mythos  ·  Grimoire

De Vermis Mysteriis

also known as Mysteries of the Worm

Ludvig Prinn

Can I actually read this? A little. Scattered lines survive in the text around it. Quoted

A Latin grimoire written in prison by a Flemish sorcerer who claimed to have survived the Ninth Crusade, and printed in Cologne the year after they burned him.

Lovecraft wanted his friends citing the same imaginary books. Bloch, still a teenager, took the invitation and then asked if he might murder the host.

Mysteries of the Worm is Bloch’s title. Lovecraft, who could not leave a made-up book in the vernacular, pencilled in De Vermis Mysteriis and Bloch kept the correction. The rest is the standard apparatus — a sorcerer too old to be believed, a cell, a posthumous Cologne edition, iron facings, a chapter you should not read aloud — except that the first time someone does read it aloud, the person who dies is a recluse in Providence with a taste for obscure volumes. Bloch had written his correspondent into the trap. Lovecraft’s reply was The Haunter of the Dark, in which Robert Blake of Milwaukee comes to a similar end.

That is the shared library at its most intimate. Not a continuity bible. A correspondence, conducted in invented bibliography, in which the citations are also the weapons.

On the readability rating. Bloch quotes the circumstances of the invocation more than the Latin. Enough of Prinn’s career is given to stock a footnote. The chapter on familiars is described by its result.

In-world history

Prinn, alchemist and reputed mage, is burned at Brussels. The manuscript is smuggled from the cell and printed at Cologne. Copies are suppressed and nevertheless turn up — one of them, a great black volume with iron facings, in a shop on South Dearborn Street. A chapter on familiars contains an invocation that summons something the invoker does not control.

Why it matters

Bloch's contribution to the shared shelf, and the one that made the sharing personal: he used it to kill a version of Lovecraft, and Lovecraft, delighted, wrote the sequel in which a version of Bloch dies in turn.

Appearances

  • The Secret in the Tomb (1935) — Robert Bloch First mention, as Mysteries of the Worm
  • The Shambler from the Stars (1935) — Robert Bloch The book is found, opened, and used; Lovecraft supplied the Latin title
  • The Haunter of the Dark (1936) — H. P. Lovecraft Written as a sequel, and as a return of the favour — Bloch had asked permission to kill a Lovecraft-shaped character

Connected volumes

Also from this world

Catalogue record

Category
Grimoire
World
The Cthulhu Mythos
Imagined by
Robert Bloch , H. P. Lovecraft
Language
Latin; later, an English translation
First appearance
"The Secret in the Tomb", Weird Tales, May 1935
Readability
Quoted
Grimoires Dangerous Books Lost Manuscripts

Sources

  • Robert Bloch, "The Shambler from the Stars", Weird Tales, September 1935; first mention in "The Secret in the Tomb", Weird Tales, May 1935.
  • H. P. Lovecraft, letter to Robert Bloch, 25 January 1935, suggesting the Latin title De Vermis Mysteriis; "The Haunter of the Dark", Weird Tales, December 1936.

Added by house · last checked 2026-09-01