Immensely powerful though we are today, it's equally clear that we're going to be even more powerful tomorrow. And what's more there will be greater … - David Attenborough

No sooner has one been pushed out of the nest then a second will follow, until there is only one left. And that's what happens nearly always in a pelican's nest. That being the case, it seems rather inefficient, not to say heartless, that the pelican should always lay three eggs. But the reason is that it's partly an insurance policy, in case something terrible happens to one or two of the chicks, there's always a third left to carry on. And partly because, very rarely, when the fishing is very good, it is possible to raise more than one chick.

I am at the very centre of the great white continent, Antarctica. The South Pole is about half a mile away. For a thousand miles in all directions, there is nothing but ice. And, in the whole of this continent, which is about one-and-a-half times the size of the United States and larger than Europe, there is a year-round population of no more than 800 people. This is the loneliest and coldest place on Earth, the place that is most hostile to life. And yet, in one or two places, it is astonishingly rich.

In moments of great grief, that's where you look and immerse yourself. You realise you are not immortal, you are not a god, you are part of the natural world and you come to accept that.