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What if the beings called demons do not all belong to the same kind?
In On Demoniality, Ludovico Maria Sinistrari asks what incubi and succubi are, and how church law should judge sexual encounters with them. An Italian Franciscan theologian and trained jurist, he approaches this strange subject through careful scholastic argument. At stake is how to define both a being and a sin.
Christian teachers such as Thomas Aquinas describe demons as fallen angels who tempt human beings. Sinistrari proposes another possibility: some beings may be a separate kind of rational creature, between humans and angels. His short treatise opens a window onto how a learned churchman reasons about spirits, desire and the unseen world.
What you’ll discover
- A question left open Follow Sinistrari into a problem that earlier writers on witchcraft leave only partly answered.
- Between humans and angels Explore his proposal that some spirits belong to a distinct kind of rational being.
- Naming a particular sin See how he defines demoniality and asks what separates it from other sins.
- The jurist's careful reasoning Encounter a theologian whose training in church law shapes his approach to supernatural questions.
- A history of belief Look closely at ideas about spirits through the arguments of a learned Franciscan friar.
Who will love it
Readers who love the odd corners of religious history, the logic of baroque scholars, and the folklore of spirits and witches will find a rich study of how learned men reasoned about the unseen.
What’s inside
The key ideas, in the 15-minute summary
- Judgment begins with the demon's nature
- A separate act needs a separate name
- The witch's pact comes before intercourse
- Some visitors seek affection without worship
- Borrowed seed leaves fatherhood unexplained
- Silence does not rule out subtle bodies
- Bodily responses suggest a natural creature
- Older accounts support creatures between kinds
- The creature's nature guides the judgment
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On Demoniality: On Incubi, Succubi & the Nature of Demons
by Ludovico Maria Sinistrari · 1875
A Pavia theologian says goblins can be driven off with musk, cardamom and brandy, and builds a doctrine on it.
ChallengingUnder 2 hours to read20 languages
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“the word Angel refers not to a kind of being but to an office.”
In short
Picture a married woman in the Italian city of Pavia. A cake she never baked arrives with her loaves from the oven.
On Demoniality: On Incubi, Succubi & the Nature of Demons at a glance
- Reading time
- About 1 h 45 min1 h 25 min fast, 2 h 5 min slow
- Length
- 25,300 words
- Library level
- Challenging long sentences, a rich vocabulary
- First published
- 1875by Ludovico Maria Sinistrari
Reading time at 238 words a minute (fast 300, slow 200). How long the classics take to read · Updated
From the 15-minute summary · Key idea 1
Demoniality is a sin of its own kind
Sinistrari opens with a question of naming. The word Demoniality was coined by John Caramuel. Before that, the schools filed intercourse with a demon under bestiality. Saint Thomas Aquinas defined bestiality as intercourse with something of a different species, and other moralists read that as covering demons too.
Sinistrari disagrees. In his view Aquinas meant a living animal. A human corpse is also a thing of another species, yet nobody calls intercourse with a corpse bestiality. It is called pollution. So the phrase cannot stretch to cover anything at all.
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- 1875
- Language
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Cite this edition
Sinistrari, Ludovico Maria. On Demoniality: On Incubi, Succubi & the Nature of Demons. Library of Alexandria, 2026, libraryofalexandria.com/products/on-demoniality-on-incubi-succubi-the-nature-of-demons.
Sinistrari, L. M. (2026). On demoniality: On incubi, succubi & the nature of demons. Library of Alexandria. https://libraryofalexandria.com/products/on-demoniality-on-incubi-succubi-the-nature-of-demons (Original work published 1875)
Sinistrari, Ludovico Maria. On Demoniality: On Incubi, Succubi & the Nature of Demons. Library of Alexandria, 2026. https://libraryofalexandria.com/products/on-demoniality-on-incubi-succubi-the-nature-of-demons.
@book{sinistrari2026demoniality,
author = {Sinistrari, Ludovico Maria},
title = {On Demoniality: On Incubi, Succubi \& the Nature of Demons},
publisher = {Library of Alexandria},
year = {2026},
url = {https://libraryofalexandria.com/products/on-demoniality-on-incubi-succubi-the-nature-of-demons},
note = {First published 1875}
}
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What is On Demoniality about?
It is a scholastic treatise on sexual intercourse between humans and demons. Sinistrari defines the sin, describes witches' pacts, argues that incubi are rational creatures with subtle bodies, and then sets out how courts should weigh, prove and punish the crime.
What is the difference between demoniality and bestiality?
Sinistrari says bestiality is intercourse with a living beast, while demoniality involves a demon who, on the common teaching, uses a lifeless body moved from outside. He argues they differ in kind, in confession and in gravity.
What are incubi and succubi in this book?
An incubus is a male demon who seeks intercourse with women, and a succubus a female one who seeks men. Sinistrari reasons that some are not fallen spirits but mortal rational beings with fine bodies of air, water or fire.
The author
Ludovico Maria Sinistrari
1622–1701 · Italian priest and writer
Ludovico Maria Sinistrari was an Italian Franciscan priest and writer. He was born in Ameno, Italy, in 1622 and died in Milan in 1701. He wrote in Latin about theology and demonology during the seventeenth century. His work on demoniality was published after his death, in 1875.
“the word Angel refers not to a kind of being but to an office.”
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