Take a moment from time to time to remember that you are alive. I know this sounds a trifle obvious, but it is amazing how little time we take to remark upon this singular and gratifying fact. By the most astounding stroke of luck an infinitesimal portion of all the matter in the universe came together to create you and for the tiniest moment in the great span of eternity you have the incomparable privilege to exist.

The whole of the global economy is based on supplying the cravings of two per cent of the world's population.

There is the odd exception, like Albert Einstein, but as a breed, scientists tend not be very good at presenting themselves.

It's hard not to be kind of pessimistic about human beings generally, because we do tend to mess things up. If you just look at the history of extinctions, we've killed off an awful lot of animals - and I don't think we're doing a very good job of looking after the planet.

On the dashboard of our family car is a shallow indentation about the size of a paperback book. If you are looking for somewhere to put your sunglasses or spare change, it is the obvious place, and it works extremely well, I must say, so long as the car is not actually moving. However, as soon as you put the car in motion ... everything slides off ... It can hold nothing that has not been nailed to it. So I ask you: what then is it for?

Energy is liberated matter, matter is energy waiting to happen.

When the poet Paul Valery once asked Albert Einstein if he kept a notebook to record his ideas, Einstein looked at him with mild but genuine surprise. "Oh, that's not necessary," he replied . "It's so seldom I have one.