Why leave the book?

[Nathaniel]

No: HPFGUIDX 137137

Jmoses22002 at y wrote:
> Why would Snape leave the HBP book in his old potions class?  



I fall into the camp of those that believe that Snape did not do it 
intentionally.  Snape had probably long since stopped using his old 
textbook.  At first, when Snape was just starting out as the potions 
master, it was helpful to have his old textbook with his improvements 
to the potions.  But after each passing year he found himself using 
it less and less. After having taught the same spells over and over 
again to students year after year he finally found himself not using 
the textbook at all.  He had done the spells himself so often, and he 
had corrected students so often that he did not need to reference it 
anymore. 

A dozen or so years of teaching and Snape simply knew everything he 
had written in the margins. Then Dumbledore finally gives the word 
that he has convinced Slughorn to come out of retirement and take the 
job of potions master. Snape is told he will indeed need to clear his 
personal effects out of the potions classroom, but Snape forgets, for 
the moment about his old textbook which he has not really used or 
thought about for many years.   He has much bigger things on his 
mind - like his recent "unbreakable vow" he has just made and how his 
roll as double agent just got considerably more difficult.  He has 
his mind on re-familiarizing himself with D.A.D.A. curriculum.  He 
simply does not recall that he has a valuable (at least to someone 
less knowledgeable about potions than he) textbook tucked away in 
some closet in his old classroom.

But the events throughout the school year serve to remind Snape about 
his old textbook.  First, there is Slughorn praising Harry's potions 
abilities at the Christmas party.  Snape the legilimens then starts 
trying to probe Harry for the sudden improvement.  He gets scattered 
images of Harry's emotions and something about an illicit textbook, 
but he gets interrupted by Draco's sneaking about the castle and is 
unable to probe further.  Then several months later he sees Draco 
with the unmistakable signs that he has fallen victim to the old 
spell he invented. He probes Harry further as a legilimens.  This 
time Harry is thinking "don't think about the Half-blood Prince" 
which is, of course, the final clue that Snape needs in order to make 
the connection - Harry has his old textbook.  

It seems to me that Snape hasn't made the connection until this 
moment.  Otherwise, there would be no point in going through the 
charade of having him retrieve his schoolbag.  If Snape had previous 
knowledge that Harry had somehow come into possesion of his textbook, 
then he would not need to have Harry go retrieve his books.  The 
serious injury to Draco would be sufficient to land Harry into 
detention for as long as Snape wishes.  Harry bringing back Ron's 
textbook was merely for Snape's own satisfaction; he wanted confirm 
his suspicions that Harry was in possesion of his old, long-
forgotten, school book.  
-Nathaniel