How we cite our quotes: (Story.Chapter.Paragraph)
Quote #1
"It's a device for making pictures quickly," said Twoflower. "Quite a new invention. I'm rather proud of it but, look, I don't think these gentlemen would—well, I mean they might be—sort of apprehensive? Could you explain it to them? I'll reimburse them for their time, of course." "He's got a box with a demon in it that draws pictures," said Rincewind shortly. "Do what the madman says and he will give you gold." (1.8.66-67)
As the story goes, when the camera was first introduced, people thought it was a demonic invention that stole your soul. Discworld is the kind of place where our impossible becomes very possible. Sure, the camera still doesn't steal souls, but that whole demon thing proves spot on.
Quote #2
Even a failed wizard knew that some substances were sensitive to light. Perhaps the glass plates were treated by some arcane process that froze the light that passed through them? Something like that, anyway. Rincewind often suspected that there was something, somewhere, that was better than magic. He was usually disappointed. (1.12.5)
On the other hand, the things that are possible in our world, such as how cameras actually work, don't pan out. Instead, the supernatural explanation is best.
Quote #3
"Can't tell you. Don't really want to talk about it. But frankly," he sighed, "no spells are much good. It takes three months to commit even a simple one to memory, and then once you've used it, poof! It's gone. That's what so stupid about the whole magic thing, you know." (1.15.41)
Most readers probably imagine that magic would make life pretty swell. How many people read Harry Potter and the Goblet of Fire and thought, "Yeah, I go could for apparition. It'd make my commute way easier." But The Color of Magic points out several instances where magic wouldn't make life any easier, and if anything, for every problem magic solves, it just causes another.