by the image, the books are lying right in front of the doorstep, as if the librarian is trying to slow down the guard from catching the thief by blocking the door with books. And he was lying saying:-
"I didn't have chance to do anything,
I tried to stop him with all my strength, but what could I do?
you should scream help first!
and why would a thief broke down a library to steal only a book! they should just come there normally, read it, or borrow it... smh. There are even many valuable things (i can see a pendant, some vase, treasurechest?, etc in the pic) there in the library to steal and yet the thief only took 1 book.