“He really really really shouldn't have done that. Amazing how much more obvious that became one second after it was too late.”

“What people really believe doesn't feel like a BELIEF, it feels like the way the world IS.”

“The glass display cases had shown rock-throwers crafted by the Australian aborigines - like giant wooden shoehorns, they'd looked, but smoothed and carved and ornamented with the most painstaking care. In the 40,000 years since anatomically modern humans had migrated to Australia from Asia, nobody had invented the bow-and-arrow. It really made you appreciate how non-obvious was the idea of Progress. Why would you even think of Invention as something important, if all your history's heroic tales were of great warriors and defenders instead of Thomas Edison? How could anyone possibly have suspected, while carving a rock-thrower with painstaking care, that someday human beings would invent rocket ships and nuclear energy?”

“Aside from helping people with their homework, or anything else they needed, she really didn't know how to meet people. She didn't feel like she was a shy person. She thought of herself as a take-charge sort of girl. And yet, somehow, if there wasn't some request along the lines of "I can't remember how to do long division" then it was just too awkward to go up to someone and say... what? She'd never been able to figure out what. And there didn't seem to be a standard information sheet, which was ridiculous. The whole business of meeting people had never seemed sensible to her. Why did she have to take all the responsibility herself when there were two people involved? Why didn't adults ever help? She wished some other girl would just walk up to her and say, "Hermione, the teacher told me to be friends with you".”

“One of chief pieces of advice I give to aspiring rationalists is "Don't try to be clever." And, "Listen to those quiet, nagging doubts." If you don't know, you don't know what you don't know, you don't know how much you don't know, and you don't know how much you needed to know.”

“Without thinking about it at all, Harry stepped in front of Hermione.There was an intake of breath from behind him, and then a moment later Hermione brushed past and stepped in front of him. "Run, Harry!" she said. "Boys shouldn't have to be in danger.”

“There are no hard problems, only problems that are hard to a certain level of intelligence. Move the smallest bit upwards [in intelligence] and some problems move from "impossible" to "obvious." Move a substantial degree upwards, and all of them will become obvious.”