Snape's potions book (was Re: Who needs Harry?)

[Zara]

No: HPFGUIDX 182336

> SusanFullin asks:
> How come Snape's book was left in school? In HBP Harry
> gets it. I should think Snape, knowing how much he added
> and worked on it, would have taken it away. Is there
> something in canon that says textbooks must be kept at
> Hogwarts??? Thanks!

zgirnius:
There is no explanation for this. My own personal explanation, is 
that Snape kept the book in the classroom for reference as a young 
teacher, but over time he has reached the point that he no longer 
refers to it.

I would guess that everything in it falls into one of two categories 
for him. It is either something he knows by heart (so that he does 
not need to look it up) or something that is outdated (in the sense 
that he has discovered an even better improvement than the ones he 
did, after all, invent as a teen).

If he has not so much as cracked the book open for a decade, I don't 
find it hard to believe he did not bother to retrieve it from the 
storage cupboard in which it was found when he took over the DADA 
teaching position.