In my heart, I'm just a kid from the council houses. I can remember the old cottage and my dad coming round with the tin bath. I'm not a rich man.

I think when people mean that Discworld books have become darker they really mean the series is growing up. In 'The Colour of Magic' most of the city is set alight. It's a joke, in much the same way that the Earth is destroyed almost at the start of Douglas Adams's 'The Hitchhikers Guide to the Galaxy.'

I grow as many of our vegetables as I can, because my granddad was a professional gardener, and it's in the blood.

I am certain no one sets out to be cruel, but our treatment of the elderly ill seems to have no philosophy to it. As a society, we should establish whether we have a policy of life at any cost.

Sound science must be our guide in choosing which problems to tackle and how to approach them.

One futuristic novel that had a huge impact on me was Mary Shelley's 'Frankenstein,' which is kind of science fiction plus Gothic.

We get the exciting result that the total energy of the universe is zero. Why this should be so is one of the great mysteries - and therefore one of the important questions of physics. After all, what would be the use of studying physics if the mysteries were not the most important things to investigate?

For many human beings, an interest in the past starts with themselves. That is, in part, a result of biology. Like other creatures, humans have a beginning and an ending, and in between lies their story.