| Quote #1
It took Harry several days to get used to his strange new freedom. Never before had he been able to get up whenever he wanted or eat whatever he fancied. He could even go wherever he pleased, so long as it was in Diagon Alley [...] (4.1.1)
Harry sort of lives out everyone's childhood dream here – what would it be like to have no adult supervision? It's fitting that this novel starts out with Harry living out a child's fantasy since, for the rest of it, Harry has to do a lot of growing up, which is a largely unpleasant business. As we'll see, growing up can involve a lot of restrictions on that very freedom.
| Quote #2
He accompanied them to the entrance hall, where Filch, the caretaker, was standing inside the front doors, checking off names against a long list, peering suspiciously into every face, and making sure that no one was sneaking out who shouldn't be going. (8.4.5)
The image here of Harry having to stay behind with Filch, who acts like a jail warden, is really powerful. Hogwarts has become a sort of prison for Harry.
| Quote #3
"The fortress is set on a tiny island, way out to sea, but they don't need walls and water to keep the prisoners in, not when they're all trapped inside their own heads, incapable of a single cheerful thought. Most of them go mad within weeks." (10.2.39)
Azkaban is really the ultimate prison since it traps people within their own minds, the worst kind of entrapment, really. However, you don't have to be in Azkaban to experience that kind of entrapment. Take Snape, for instance, who's so consumed with rage over the past that he's basically trapped by it. What other characters are trapped in their own heads or by their own emotions?