Why doesn't the shopkeeper in Harry Potter & the Prisoner of Azkaban use Accio to find the missing Invisibility books?

Question

I have recently started reading through the Harry Potter series yet again and noticed something quite peculiar in Harry Potter and the Prisoner of Azkaban; while shopping at a wizarding book store (sorry, can't remember the name), the store owner cries out in frustration, obviously irritated by the newest book, The Monster Book of Monsters, yelling.

"I'm never stocking these again, never! This is worse than when we ordered over 200 copies of the Invisible Book of Invisibility; never could find them."

Couldn't the shopkeeper have used the Accio spell to summon the books, or was it implied at some point in the Harry Potter universe that this book owner is actually a Squib, and therefore cannot perform magic? I have not yet found any answer on this, and any help would be appreciated.

Answer 1

It's entirely possible that the owner wasn't able to sufficiently distinguish between his copies of the books and others that may have been in the area - he'd certainly get into legal trouble if he Acciod other people possessions and tried to sell them!

That said, there's no indication that he's a squib - while he never does onscreen magic, neither do most of the other witches and wizards we see.

For myself, I've always taken that line as it was likely intended - a humorous throwaway that shows that there is a larger magical world, but was never intended to be explored in a deeper way.

The owner could also have been having some fun at the expense of the students - if he was a capable wizard, he could certainly have used any number of spells to retrieve the books, ranging from the levitating charm to the summoning charm, even up to something like Petrificus Totalis or Stupify.

Answer 2

The Summoning Charm is used to make an object fly from a particular place to the casters arms. The incantation for the charm is 'Accio'.

_{^{http://pottermore.wikia.com/wiki/Summoning_Charm}}

To summon an item to himself, a wizard has to concentrate hard on the object.

“That doesn’t matter,” said Hermione firmly. “Just as long as you’re concentrating really, really hard on it, it’ll come. Harry, we’d better get some sleep... you’re going to need it.”

_{^{Harry Potter and the Goblet of Fire, Chapter 20, The First Task}}

During the first task.

Harry didn’t know or care. It was time to do what he had to do... to focus his mind, entirely and absolutely, upon the thing that was his only chance.

He raised his wand.

“Accio Firebolt!” he shouted.

_{^{Harry Potter and the Goblet of Fire, Chapter 20, The First Task}}

Now imagine a shopkeeper, who gets his delivery of 200 Invisible Book of Invisibility and stocks it somewhere. Since the books are invisible, he could not have seen them. So he won't be able to concentrate on the books, when he has to summon them. He would mostly think of empty space instead of book while summoning them. So the spell may not work.