"By knowing what I care about, and which of those things I care about more," Bella says.
"Then what do you do instead? If you know some stuff matters and some stuff doesn't."
Bella decides she's not going to get a satisfactory answer to this question. "Sure."
"I don't have, like, a master list," Bella says. "With everything all outlined neat. Maybe I should, but mostly it's all scattered around between notebooks and I have the general idea memorized and know where to look for details if I can't come up with them."
"Then I notice that when I look again, and then I figure out why, and try to find out if it's going to happen again and if I want to let it."
"What I really wanted - if I was sure about what that was. Sometimes I might not be. If I was scared or mad or something, I might feel like I really wanted to do something that I'd know was a bad idea if I was thinking clearer. And then I'd have to sort of - step back and remember why I wrote what I wrote, and see if those reasons are still there, and see if I trust my brain however it's being right then."
Bella thinks about this. "Maybe not all of it," she says. "But some of it sure."
"I care about privacy, that'd be on the list," she says with a little laugh. "That's why I wanna learn Occlumency."
"Huh. So you wouldn't care that much if somebody Legilimencied you and could see - all your memories - and what you were thinking?"
"Not just to mindread," Bella says. "I don't want to mindread anybody who doesn't want to be mindread. It's just, I can't find out how you're supposed to learn Occlumency, and I could make stuff up but I don't know how I'd tell if the stuff I was making up was even sorta right, without - testing it."