“Oh, we're very careful, Marilla. And it's so interesting. Two flashes means, "Are you there?" Three means "yes" and four "no." Five means, "Come over as soon as possible, because I have something important to reveal." Diana has just signalled five flashes, and I'm really suffering to know what it is.”

“I've got a few ideas," (Amy) admitted. "But I don't know where we're going in the long term. I mean - have you ever thought about what this ultimate treasure could be?""Something cool." (Dan)"Oh, that's real helpful. I mean, what could make somebody the most powerful Cahill in history? And why thirty-nine clues?"Dan shrugged. "Thirty-nine is a sweet number. It's thirteen times three. It's also the sum of five prime numbers in a row - 3,5,7,11,13. And if you add the first three powers of three, 3 to the first, 3 to the second, and s to the third, you get thirty-nine."Amy stared at him. "How did you know that?""What do you mean? It's obvious.”

“I have already spent roughly five thousand hours asleep next to you. This has to mean something.”

“Do you remember the section on controlling demons in Demonologies? I believe it's in chapter five.""Um...no."Irritation flashed over his face. "Honestly, Sophie, I gave you that book for a reason.""And I'm really sorry, but it's long and boring,and can we just skip to the part where you tell me what it says?”

“The flash would prove that proton decay really happens. The flash would mean that the matter of the proton - the solid stuff - had turned into the energy of the flash (E-mc2). Totally. Nothing left behind. No ash. No smoke. No smell. Nada. One moment it's there, the next moment - pffft - gone. What would it mean? Only this: Nothing lasts. Nothing. Because everything that exists is made of protons.”

“Skye: Did you really mean what you just said up there?Craig: Yes... and so much more. Three years too late, I guess.Skye: It's never too late.”