The book I'm talking about is 'Secrets of the Darkest Arts' (which is the only book covering the subject of horcruxes to my knowledge). Riddle presumably read this book prior to him asking Slughorn about them as he already knew what they were (he just wanted information on how to make multiple horcruxes). Anyway, why did they keep the book in the library (although in the restricted section) if it was a banned subject (Slughorn told Riddle the subject was banned when asked about them). Basically any student could have found the book and learned about them.

  • 4
    'Secrets of the Darkes Arts' contains explicit information on how to make horcruxes. Dumbledore removed the book from the library later on after Riddle asked Slughorn about them, but by that point the damage was already done.
    – silverpaw
    Jul 27, 2016 at 19:23
  • I'll accept that. I didn't remember Hermione's quote.
    – Valorum
    Jul 27, 2016 at 19:30
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    @silverpaw From the first book we know what happens when a student tries to sneak into the Restricted Section.
    – Scimonster
    Jul 28, 2016 at 7:30
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    @Scimonster My point is that older students could've gotten their hands on the horcrux book before it was removed (which Riddle most likely did). So they didn't want students to know about the existence of horcruxes but they let the horcrux book lay around for any "authorized" student to pick it up. Makes sense... And again, it's only speculation whether all the books are enchanted. We don't know that.
    – silverpaw
    Jul 28, 2016 at 15:28
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    It was banned later? Slughorn only says to Tom that no one would want "...existence in such a form" and that it's very dark. But it's knowledge, probably one of the failed experiments in the pursuit of immortality, so it was preserved and even the Hogw. libraty contained some info on it.
    – user68762
    Aug 23, 2016 at 14:24

4 Answers 4


According to Slughorn there may not have been much about Horcruxes in the library to begin with.

‘No ... well ... you’d be hard-pushed to find a book at Hogwarts that’ll give you details on Horcruxes, Tom. That’s very Dark stuff, very Dark indeed,’ said Slughorn. - -Half Blood Prince

The books that did mention Horcruxes were removed from the library, we are just unsure when it occurred exactly.

‘And once we get hold of it, how do you destroy a Horcrux?’ asked Ron.

‘Well,’ said Hermione, ‘I’ve been researching that.’

‘How?’ asked Harry. ‘I didn’t think there were any books on Horcruxes in the library?’

‘There weren’t,’ said Hermione, who had turned pink. ‘Dumbledore removed them all, but he – he didn’t destroy them.’ -Deathly Hallows

And again later in the same chapter Hermione states this, showing Slughorn may have been mistaken.

‘This is the one that gives explicit instructions on how to make a Horcrux. Secrets of the Darkest Art – it’s a horrible book, really awful, full of evil magic. I wonder when Dumbledore removed it from the library ... if he didn’t do it until he was Headmaster, I bet Voldemort got all the instruction he needed from here.’

We can probably safely assume that when Dumbledore was made Headmaster he would have removed them for sure, but I believe that the fact that Slughorn mentions how strongly Dumbledore was against Horcruxes when speaking to Riddle he may have already removed the books.

It’s a banned subject at Hogwarts, you know ... Dumbledore’s particularly fierce about it ...’ - Half Blood Prince

Three points to note.

  1. We don't know when this ban went into effect in the 1000 years of Hogwarts' existence, before Slughorn's conversation. Dumbledore himself may have been the root cause of the ban.

  2. Being a banned subject may only mean it's not taught in school, while owning a book that contains details about it in the restricted section of the library for study by advanced students may be, or was, allowed.

  3. Finally, Hogwarts is not the only location in which books can be found, and Voldemort likes to cover his trail and keep up his good boy persona (in school), so finding books on Horcruxes outside of school would have appealed to him as well.

  • 1. Slughorn told Riddle it was a banned subject when he asked about them, so presumably the ban was already in effect during that time.
    – silverpaw
    Jul 27, 2016 at 19:33
  • @silverpaw yes, i stated that.
    – Himarm
    Jul 27, 2016 at 19:33
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    @silverpaw banning something and enforcing a ban are to different things. Dippet seems to be an unobservant headmaster he could have simply not cared for forgot, previous head masters may have had the ban thrust on them from the board of directors(or whatever board ran the school) but not supported the ban hence leaving the books, so we really cant say definitively if its a plot hole or not
    – Himarm
    Jul 27, 2016 at 19:43
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    On second note: also banned subjects are taught in school. Unforgivable curses are banned but 'barty crouch jr. moody' tells in the first lesson that he shouldn't be showing the curses until 7. grade. So Hogwarts teaches the curses but it is still forbidden to use them Jul 28, 2016 at 10:18
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    Additionally, it is mentioned that 'Secrets of the Darkest Art' contained information on things other than Horcruxes which could have been enough to land it in the restricted section instead of removing it all together. I could see a Horcrux-only book being removed but a book where Horcruxes are only one chapter in the book being kept around with tighter access restrictions.
    – Kapler
    Jul 29, 2016 at 20:14

Books in the restricted section are, as we see in Chamber of Secrets, not usually available to students. They need express permission in writing from a teacher for every book they want to access:

‘Er – Professor Lockhart?’ Hermione stammered. ‘I wanted to – to get this book out of the library. Just for background reading.’ She held out the piece of paper, her hand shaking slightly. ‘But the thing is, it’s in the Restricted Section of the library, so I need a teacher to sign for it – (…)’


Madam Pince held the note up to the light, as though determined to detect a forgery, but it passed the test. She stalked away between the lofty shelves and returned several minutes later carrying a large and mouldy-looking book.

(Harry Potter and the Chamber of Secrets, chapter The rogue Bludger)

Apparently, Amando Dippet and his predecessors believed that to be sufficiently safe. It wasn’t before Dumbledore had become Headmaster (after Riddle had asked Slughorn about Horcruxes) that the books about Horcruxes were removed from the library altogether.

  • Yes, but it seems strange that they kept the book around if they didn't want anyone to know about horcruxes. It would've been more logical to remove the book immediately after the subject was banned.
    – silverpaw
    Jul 27, 2016 at 19:26
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    @silverpaw: The place to be for library books is in the library. It’s highly unusual for serious (scientific) libraries to destroy a book or magazine, ever; even for dangerous books (say, describing how to make certain poisons or how to construct a bomb), it’s considered enough to place them in a ‘poison cabinet’, i.e. a restricted section.
    – chirlu
    Jul 27, 2016 at 19:49
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    @silverpaw: Did you read what I wrote? “Students need express permission in writing from a teacher for every book they want to access.” Now, Riddle is a master in social engineering; certainly not “any student” could have done the same.
    – chirlu
    Jul 27, 2016 at 20:04
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    @silverpaw As we saw, there are enchantments on the books in the Restricted Section that prevent unauthorised reading - we know they can scream, and no doubt there are other defences on the worst volumes; Madam Pince is known to be fiercely protective of her books. Harry's invisibility cloak is literally the best in the world, and the teachers who were awake were mostly distracted with trying to steal or protect the Philosopher's Stone. I doubt there are more than a handful who could manage it, and few of them would be inclined to actually try it. Jul 28, 2016 at 9:06
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    Just because older students can browse the shelves doesn't mean the books aren't enchanted - it just means that the enchantment knows when a reader isn't allowed to be reading the book. An upper-year student reading book on making horcruxes is likely similar to a Muggle forensics student reading a book that could tell them how to commit the perfect murder, or a chemical engineering student reading a book that talks about mixing explosives: dangerous in the wrong hands, but surely these students can be trusted? After all, for them to actualy do it would be unthinkable... Jul 28, 2016 at 15:26

Others may not be as ‘fierce’ as Dumbledore.

Horcruxes were considered a banned subject at Hogwarts during Voldemort’s time as a student, which may have been in no small part due to Dumbledore’s influence there.

“But all the same, Tom … keep it quiet, what I’ve told – that’s to say, what we’ve discussed. People wouldn’t like to think we’ve been chatting about Horcruxes. It’s a banned subject at Hogwarts, you know … Dumbledore’s particularly fierce about it …”
- Harry Potter and the Half-Blood Prince, Chapter 23 (Horcruxes)

Previous headmasters may not have felt as strongly as Dumbledore, and left the books for educational purposes. The degree to which subjects are banned likely depends on the headmaster’s judgement - when Dumbledore became headmaster, he removed the books referencing Horcruxes entirely. The previous headmasters may have simply not seen the need for this specific measure.


Although it was a banned subject, it was in the restricted section where students weren't allowed to dawdle around.

  • Students are allowed to browse the restricted section so pretty much anyone could've gotten their hands on the book, which seems strange as it they didn't want students to know about the existence of horcruxes.
    – silverpaw
    Jul 28, 2016 at 5:47
  • students could not browse the restricted section without permission from their teachers.
    – Beez
    Jul 28, 2016 at 5:52
  • We don't know if that rule applies to older students, but even if it did, students can sneak in anyway so we know that the "permission" thing can be circumvented.
    – silverpaw
    Jul 28, 2016 at 14:45

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