Plot Oversight in PS/SS?

[Geoff Bannister]

No: HPFGUIDX 138861

--- In HPforGrownups at yahoogroups.com, "Derek Hiemforth" <derek at r...> 
wrote:
> I've been re-reading the whole series recently (since finishing
> HBP), and a thought struck me.  Please let me know if this has
> occurred to anyone else, or if I'm just overlooking something
> very obvious.
> 
> In PS/SS, the professors set up the protections for the Stone
> at the beginning of the year.  Hagrid obtained the stone
> before the start of term, and, by the opening feast,
> Dumbledore warns the students about the third-floor area,
> so Fluffy must already be up there.  Hagrid provides Fluffy,
> Sprout the Devil's Snare, Flitwick the flying keys, McGonagall
> the  chessboard, Snape the potions puzzle...
> 
> ...and Dumbledore the Mirror of Erised.
> 
> So if the Mirror of Erised has been guarding the Stone since
> the start of the year, down behind a gauntlet of traps, how is
> Harry able to stumble across it around Christmas time in an
> empty classroom?

Geoff:
Because, in my own view at least, I don't see the Mirror as being 
part of the protections around the Philsopher's Stone. You don't have 
to get past the Mirror in order to reach the dungeon.

It was no good to Quirrell even when it had been moved. He couldn't 
work out what to do...

'"This mirror is the key to finding the Stone... Quirrell murmured, 
tapping his way around the frame. "Trust Dumbledore to come up with 
something like this... but he's in London..."

...Quirrell came back out from behind the Mirror abd stared hungrily 
into it.
"I see the Stone... I'm presenting it to my master... but where is 
it?"'

(Philosopher's Stone, "The Man with Two faces" p.210 UK edition)

So the Mirror is showing him his heart's desire but that is all. 
Dumbledore makes it clear why Quirell could not have got it...

'"And, sir, there's one more thing..."
"Just the one?"
"How did I get the Stone?"
"Ah, now, I'm glad you asked me that. It was one of my more brilliant 
ideas and, between you and me, that's saying something. You see, only 
one who wanted to find the Stone - find it, but not use it - would be 
able to get it..."'

(ibid. p.217)

So the only person who benefited from the Mirror's presence there was 
Harry. It was not part of the aggressive protections at all.