Snape's Fury (was: The Shrieking Shack-did Snape have ulterior motives?)

[corinthum]

No: HPFGUIDX 85855

Eloise wondered:

> After OoP, however, I am left wondering a few things.
> If Snape and Dumbledore are such experts at occulomency, I wonder 
how between 
> them they were not able to divine who was the spy in the Order of 
the 
> Phoenix. OK, I let Snape off this one, as I assume he was working 
deep under cover 
> and the members of the OoP didn't know about him. But Dumbledore?
> 
> But how come Snape didn't suss Crouch!Moody? Was he really so 
intimidated by 
> Moody's apparent suspicion of him that he was unable to divine his 
true 
> nature?  

First point, we have been given no indication that Snape is an expert 
legilimens, only occlumens.  The two seem to be completely separate 
skills.  So I don't find it strange that he wasn't able to figure 
these things out.

Now, Dumbledore, on the other hand...  

First, I don't think legilimency in general is the same thing as 
the "Legilimens" spell.  The latter, as we have seen, causes the 
recipient to flash through an assortment of memories, and allows the 
caster to see the same.  These memories appear to static, neutral 
visions, not imparting any information about the situation other than 
what is seen (Snape doesn't know, as Memory!Harry did, who the dog 
belonged to, etc.).

Legilimency, as Snape describes it earlier, strikes me as an 
imprecise form of magic, which deals more with abstract thoughts than 
specific memories.  When performing legilimency on another person, 
one is able to perceive certain emotions, and by correctly 
interpreting these emotions, is able to determine whether a person is 
lying, among other things.  Like our lie detectors, legilimency is 
not infallible, especially when the liar knows which emotions to hide.

On top of this, the emotions associated with a particular lie are not 
isolated from a person's other thoughts.  The members of the original 
order were part of a secret, underground organization.  Whenever they 
met, I'm sure several members had to tell various lies to their 
friends, family, etc.  They were all aware that they were involved in 
a dangerous operation.  Many of them had probably been trained for 
undercover work even if they didn't know Occlumency.  Overall, 
Dumbledore would be trying to find a liar amongst a group of people 
trying with all their might to keep dozens of lies straight in their 
minds.  Could he really be expected to distinguish Peter's lie from 
the others?  And really, Peter didn't have to do much active lying in 
Dumbledore's presence.  

-Corinth