How we cite our quotes: Citations follow this format: (Chapter.Paragraph)
Quote #1
"But, perhaps, I keep no journal"
"Perhaps you are not sitting in this room, and I am not sitting by you. These are points in which a doubt is equally possible. Not keep a journal! [...] How are the civilities and compliments of every day life to be related as they ought to be, unless noted down every evening in a journal?" (3.26-7)
Henry jokingly links journals to civilized life. The journals Henry speaks of are extensions of polite society, with certain rules that are followed.
Quote #2
Yes, novels; - for I will not adopt that ungenerous and impolitic custom, so common with novel writers, of degrading by their contemptuous censure the very performances, to the number of which they are themselves adding - joining with their greatest enemies in bestowing the harshest epithets on such works, and scarcely ever permitting them to be read by their own heroine. (5.4)
Lots of novels don't let their heroines read novels, but Northanger Abbey prominently features Catherine reading novels. Catherine is "corrupted" by her reading habits, much as these other heroines feared they would be. Catherine's corruption is not a serious matter though. Instead it is funny.
Quote #3
"Oh! I am delighted with the book! I should like to spend my whole life in reading it. I assure you, if it had not been to meet you, I would not have come away from it for all the world." (6.7)
Catherine is showing signs of being obsessed with Gothic novels here, since she is reluctant to go out and socialize.