Rincewind and the Picture Box and the Logic (or lack thereof really) of Life on the Disc
In the long afternoon they toured the city Turnwise of the river. Twoflower led the way, with the strange picture box slung on a strap around his neck.
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.
Twoflower had posed alongside a bewildered charm seller, his crowd of newfound admirers watching him with interest in case he did something humorously lunatic.
Rincewind got down on one knee, the better to arrange the picture, and pressed the enchanted lever.
The box said, "It's no good. I've run out of pink."
A hitherto unnoticed door opened in front of his eyes. A small, green and hideously warty humanoid figure leaned out, pointed at a color-encrusted palette in one clawed hand, and screamed at him.
"No pink! See?" screeched the homunculus. "No good you going on pressing the lever when there's no pink, is there? If you wanted pink you shouldn't of took all those pictures of young ladies, should you? It's monochrome from now on, friend. All right?"
"All right. Yeah. Sure," said Rincewind. In one dim corner of the little box he thought he could see an easel, and a tiny unmade bed. He hoped he couldn't.
"So long as that's understood," said the imp, and shut the door. Rincewind thought he could hear the muffled sound of grumbling and the scrape of a stool being dragged across the floor.
"Hey, look—this is all wrong. When Twoflower said they'd got a better kind of magic in the Empire I thought—I thought…"
The imp looked at him expectantly. Rincewind cursed to himself.
"Well, if you must know, I thought he didn't mean magic. Not as such."
"What else is there, then?"
Rincewind began to feel really wretched. "I don't know," he said. "A better way of doing things, I suppose. Something with a bit of sense in it. Harnessing—harnessing the lightning, or something."
The imp gave him a kind but pitying look.
"Lightning is the spears hurled by the thunder giants when they fight," it said gently. "Established meteorological fact. You can't harness it."
"I know," said Rincewind miserably. "That's the flaw in the argument, of course."
The imp nodded, and disappeared into the depths of the iconograph. ... The imp reappeared.
"I've been thinking about what you said," it said before Rincewind could open his mouth. "And even if you could get a harness on it, how could you get it to pull a cart?"
"What the hell are you talking about?"
"Lightning. It just goes up and down. You'd want it to go along, not up and down. Anyway, it'd probably burn through the harness."
Currently Twoflower was showing a great interest in the theory and practice of magic.
"It all seems, well, rather useless to me," he said. "I always thought that, you know, a wizard just said the magic words and that was that. Not all this tedious memorizing."
Rincewind agreed moodily.
"Rincewind thinks he ought to be able to harness the lightning," said the picture imp, who was observing the passing scene from the tiny doorway of the box slung around Twoflower's neck. He had spent the morning painting picturesque views and quaint scenes for his master, and had been allowed to knock off for a smoke.
"When I said harness I didn't mean harness," snapped Rincewind. "I meant, well, I just meant that—I dunno, I just can't think of the right words. I just think the world ought to be more sort of organized."
"That's just fantasy," said Twoflower.
"I know. That's the trouble." Rincewind sighed again. It was all very well going on about pure logic and how the universe was ruled by logic and the harmony of numbers, but the plain fact of the matter was that the Disc was manifestly traversing space on the back of a giant turtle and the gods had a habit of going around to atheists' houses and smashing their windows.
The Colour of Magic - Terry Pratchett