“Words are the litmus paper of the mind.”

“Words are the litmus paper of the minds. If you find yourself in the power of someone who will use the word "commence" in cold blood, go somewhere else very quickly. But if they say "Enter", don't stop to pack.”

“Mind you, the Elizabethans had so many words for the female genitals that it is quite hard to speak a sentence of modern English without inadvertently mentioning at least three of them.”

“She gazed out across the rooftops of Ankh-Morpork and reasoned like this: writing was only the words that people said, squeezed between layers of paper until they were fossilized (fossils were well known on the Discworld, great spiraled shells and badly constructed creatures that were left over from the time when the Creator hadn't really decided what He wanted to make and was, as it were, just idly messing around with the Pleistocene). And the words people said were just shadow of real things. But some things were too big to be really trapped in words, and even the words were too powerful to be completely tamed by writing.”

“Theres no stink more sorrorful than the stink of wet, burnt paper. It means: the end.”

“An' you told him what I said about a verbal contract not being worth the paper it's printed on?”

“That doesn't sound very reliable to me," said the druid nastily. "How can a book know what day it is? Paper can't count.”