We do not know how much of the environmental change is due to human activities and how much [is due] to long-term natural processes over which we have no control.

The pain of childbirth is not remembered. It's the child that's remembered.

Science is not a collection of truths. It is a continuing exploration of mysteries.

Theory said one thing and the experiment said something different, so that was the stimulus that started me going, that there was something there to be explained, which wasn't understood and to try to see why that experiment gave the answer it did, so it was a big opportunity for a young student starting to have actually an experiment which contradicted the theory, so that's was my chance to understand that.

The essential fact which emerges ... is that the three smallest and most active reservoirs ( of carbon in the global carbon cycle), the atmosphere, the plants and the soil, are all of roughly the same size. This means that large human disturbance of any one of these reservoirs will have large effects on all three. We cannot hope either to understand or to manage the carbon in the atmosphere unless we understand and manage the trees and the soil too.

The technologies which have had the most profound effects on human life are usually simple. A good example of a simple technology with profound historical consequences is hay. ... It was hay that allowed populations to grow and civilizations to flourish among the forests of Northern Europe. Hay moved the greatness of Rome to Paris and London, and later to Berlin and Moscow and New York.

To me, mathematics is like playing the violin. Some people can do it - others can't. If you don't have it, then there's no point in pretending.