Because we humans are big and clever enough to produce and utilize antibiotics and disinfectants, it is easy to convince ourselves that we have banished bacteria to the fringes of existence. Don't you believe it. Bacteria may not build cities or have interesting social lives, but they will be here when the Sun explodes. This is their planet, and we are on it only because they allow us to be.

In France, a chemist named Pilatre de Rozier tested the flammability of hydrogen by gulping a mouthful and blowing across an open flame, proving at a stroke that hydrogen is indeed explosively combustible and that eyebrows are not necessarily a permanent feature of one's face.

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.

It is always quietly thrilling to find yourself looking at a world you know well but have never seen from such an angle before.

Even though sugar was very expensive, people consumed it till their teeth turned black, and if their teeth didn't turn black naturally, they blackened them artificially to show how wealthy and marvelously self-indulgent they were.

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

Houses aren't refuges from history. They are where history ends up.