"I refuse to answer that question on the grounds that I don't know the answer."

For instance, on the planet Earth, man had always assumed that he was more intelligent than dolphins because he had achieved so much - the wheel, New York, wars and so on - whilst all the dolphins had ever done was muck about in the water having a good time. But conversely, the dolphins had always believed that they were far more intelligent than man - for precisely the same reasons.

I love deadlines. I like the whooshing sound they make as they go by.

"I'd far rather be happy than right any day." Slartibartfast

In the beginning the Universe was created. This has made a lot of people very angry and has been widely regarded as a bad move.

Marvin: "I am at a rough estimate thirty billion times more intelligent than you. Let me give you an example. Think of a number, any number."
Zem: "Er, five."
Marvin: "Wrong. You see?"

DON'T PANIC.

"If there's anything more important than my ego around, I want it caught and shot now."

The ships hung in the sky in much the same way that bricks don't.

"You know," said Arthur, "it's at times like this, when I'm trapped in a Vogon airlock with a man from Betelgeuse, and about to die of asphyxiation in deep space that I really wish I'd listened to what my mother told me when I was young."
[Ford Prefect:] "Why, what did she tell you?"
[Arthur:] "I don't know, I didn't listen."

"Time is an illusion. Lunchtime doubly so."

Arthur: "Marvin, any ideas?"
Marvin: "I have a million ideas. They all point to certain death."

There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable.

There is another theory which states that this has already happened.

A learning experience is one of those things that says, 'You know that thing you just did? Don't do that.'

"My capacity for happiness," he added, "you could fit into a matchbox without taking out the matches first"