“Shall I tell you what I think the dwarfs were looking for, Mister Vimes? Something of theirs. It is a thing that talks. And they found it, and I think what it had to say directly caused five deaths. I believe I know how to find the secret of Koom Valley. In a few weeks, everyone will be able to. You must solve it, too, before the war sweeps up all of us.”
“How do you know all this?” said Vimes.
“Because I’m magical,” said the voice from the hood.
“Oh, well, if that’s the way you’re –” Vimes began.
“Patience, Commander,” said Mr. Shine. “I just… simplified. Accept, instead, that I am very… smart. I have an analytical mind. I’ve studied the histories and lore of my hereditary enemy. I have friends who are dwarfs. Quite knowledgeable dwarfs. Quite… powerful dwarfs, who wish for an end to this stupid feud as much as I do. And I have a love of games and puzzles. The Codex was not a terrible challenge.”
“If it’s going to help me find the murderers of those dwarfs in the mine then you should tell me what you know!”
“Why trust what I say? I am a troll, I’m partisan, I might wish to direct your thoughts down the wrong path.”
“Maybe you’ve already!” said Vimes hotly. He knew he was making a fool of himself; it only made him angrier.
“Good, that’s the spirit!” said Mr. Shine. “Test all that I’ve told you! Where would we be if Commander Vimes relied on magic, eh? No, the secret of Koom Valley must be found by observation and questioning and facts, facts, facts. Possibly I’m helping you find them a little quicker than you might otherwise do. You just have to think about what you know, Commander.”

– Mr. Shine on Commander Vimes |
Terry Pratchett, Thud!