Harry was thinking about the Goblin Rebellions and goblins' ongoing resentment at not being allowed to own wands and certain facts which hadn't been in the first-year History textbook, which Harry had guessed at by pattern-matching and which Professor Flitwick had confirmed in a very quiet voice. Lord Voldemort had killed goblins as well as wizards - an incredibly stupid move on Lord Voldemort's part, unless Harry was really missing something.

Of course, Harry is really missing something; and he should be noticing his confusion about this. It's a failing that he isn't. For some reason, he seems very resistant to the idea that Voldemort was actually smart. I wonder if Harry's going to realize what he's missing before the big final battle in which the villain monologues his secret plan.