Occlumency VERY VERY LONG

[pippin_999]

No: HPFGUIDX 191720

> 
> Pippin:
> <SNIP>
> > As to why Snape hides some of his memories in the Pensieve, he's got to make Voldemort think he's a less accomplished occlumens than he really is, so Snape and Dumbledore are pretending that Snape can't be really sure of protecting his memories without help.
> 
> Alla:
> 
> Could you please remind me the canon for this? Thank you.
>

Voldemort is the most powerful legilimens who has ever existed and believes Snape can hide nothing from him. Snape's life depends on this being so. HPB ch 2

Every lesson, Snape makes a  show of hiding his memories in the pensieve. OOP ch 24

When Harry breaks through Snape's defenses during the lesson, Snape appears to reassure himself that the pensieve is still secure OOP 26

Harry believes the pensieve is being used so that he can't accidentally get through Snape's defenses and see something Snape wants to hide. OOP ch 28

Dumbledore tells Harry  of the danger that Voldemort would use the occlumency lessons   against the teacher "he would seize his chance to use you as a means to spy on me." Dumbledore wished to discourage this. OOP ch 37

Voldemort never detected the memories which Snape gave to Harry in DH  and which were obviously not being protected in the Pensieve at the time.  DH ch 32

It then becomes certain that Snape knew how to hide his memories from Voldemort, and by extension Harry himself or Voldemort spying through Harry, without the aid of a pensieve.  But it was essential to keep Voldemort from suspecting this. Therefore, by using the pensieve and letting Harry know he was using it, Snape made   an obvious show of not relying on occlumency to protect his memories. 

"Do you think the Dark Lord has not asked me each and every one of these questions? And do you really think that, had I not been able to give satisfactory answers, I would be sitting here talking to you?
  She hesitated.
"I know he believes you, but..."
"You think he is mistaken? Or that I have somehow hoodwinked him? Fooled the Dark Lord, the greatest wizard, the most accomplished Legilimens the world has ever seen?"

HBP 2

Pippin