When Severus Snape attempted to make the Marauder's map "yield the information it conceals" and whatnot, how could it insult him in the way it did?

Specifically, it talked about how he was a professor, something I doubt any of the Marauders knew or could foresee when they made the map.


3 Answers 3


According to J.K. Rowling on Pottermore...

The magic used in the map's creation is advanced and impressive; it includes the Homonculous Charm, enabling the possessor of the map to track the movements of every person in the castle, and it was also enchanted to forever repel (as insultingly as possible) the curiosity of their nemesis, Severus Snape.

So apparently it was specifically designed to detect Snape, not simply anyone. (There's actually a whole article about that charm on the HP Wikia.) Thus, the personal nature of the insults (i.e. "abnormally large nose" and such) were clearly pre-programmed by the Marauders.

As for knowing he was a professor, many magical objects in the HP universe display awareness or semi-awareness, such as paintings that can hold conversations or cars that can become loyal or resentful. Apparently the map was aware enough to recognize who was reading it, and discern certain things about them.

Maybe it was listening when Harry mentioned "Professor Snape" at some point, or maybe it "just knows" through some abstract discernment spell, I doubt we'll ever know specifically.

  • 8
    An abstract discernment spell sounds like an amazing magical power. "I call Abstract Discrnment and discover that you like potatoes, but hate leeks"
    – AJFaraday
    Aug 25, 2015 at 8:51
  • 1
    Well, it also could display the names of all the new students and teachers that came to the school every year. With the same ability that lets it know those, it should be quite trivial to detect that Snape became a professor.
    – Bergi
    Aug 26, 2015 at 22:00

Snape announces his own title:

"Professor Severus Snape, master of this school, commands you to yield the information you conceal!" Snape said, hitting the map with his wand.

I'm not sure if that's in the movies, but from the book it seems fairly clear.


The map knows the Snape spends nearly 24 hours a day at Hogwarts, and has done so for long enough that he can't be a student. It knows where he lives, sleeps, eats, that he stands at the front of the classroom instead of sitting in one of the chairs, how much time he spends in the staffroom. What could he possibly be other than a professor?

The Marauder's Map is basically the NSA. It knows everything.

  • 2
    Haha this is certainly plausible and an interesting departure from the thought processes of the other answers.
    – Alex W
    Aug 25, 2015 at 17:35
  • 1
    I don't agree with this as the real answer, but it's definitely hilarious and clever.
    – xdhmoore
    Aug 26, 2015 at 20:57
  • 5
    And then they say that metadata reveals nothing…
    – Bergi
    Aug 26, 2015 at 22:02
  • 1
    This answer is brilliant. Crazy to see how current events changes our thinking about stuff like this.
    – xdhmoore
    Aug 27, 2015 at 0:52

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