Protons give an atom its identity, electrons its personality. - Bill Bryson

"Wow, look at all the places you can park,” he said, as if for all these years he had been cruising endlessly, unable to terminate a journey. For about a year the most dangerous place to drive in Des Moines was the parking lot of Merle Hay Mall because of all the cars speeding at joyous random angles across its boundless blacktop without reflecting that other happy souls might be doing likewise.

Most of the time I am sunk in thought, but at some point on each walk there comes a moment when I look up and notice, with a kind of first-time astonishment, the amazing complex delicacy of the words, the casual ease with which elemental things come together to form a composition that is — whatever the season, wherever I put my besotted gaze — perfect.

As we parted at the Natural History Museum in London, I asked Richard Fortey how science ensures that when one person goes there's someone ready to take his place.

He chuckled rather heartily at my naiveté. 'I'm afraid it's not as if we have substitutes sitting on the bench somewhere waiting to be called in to play. When a specialist retires or, even more unfortunately, dies, that can bring a stop to things in that field, sometimes for a very long while.'

And I suppose that's why you value someone who spends forty-two years studying a single species of plant, even if it doesn't produce anything terribly new?'

'Precisely,' he said, 'precisely.' And he really seemed to mean it.