I did pick up the book in the thieves' guild.
Since your inventory without any books or chests
or other (are there other?) containers isn't
constrained by space, why would you want to
add the weight of that book (a whopping 5 lbs)
if it isn't going to have any weight reducing
effect? For neatness? Can you access your
hotkeyed potions or traps if they're stored in a
container? I put my teleporter stone in the book
and it wouldn't let me use it unless it was in my
general inventory.
Am I missing something? (quite possibly)
