Every intelligent being, whether it breathes or not, coughs nervously at some time in its life.

Time is a drug. Too much of it kills you.

In the beginning there was nothing, which exploded.

That's Third Thoughts for you. When a huge rock is going to land on your head, they're the thoughts that think: Is that an igneous rock, such as granite, or is it sandstone?

What's a philosopher?' said Brutha.
Someone who's bright enough to find a job with no heavy lifting,' said a voice in his head.

Don't you understand?" snarled Rincewind. "We are going over the Edge, godsdammit!"
"Can't we do anything about it?"
"No!"
"Then I can't see the sense in panicking," said Twoflower calmly.