A bird needs to be able, for example, to pick out a seed against the background of grit on which it lies, to pick up a particular twig to build a nest, and so on. But if that is the only attention it is paying, it will soon end up as someone else's lunch while it is getting its own, because it needs at the same time to pay a quite different type of attention to the world – a broad, open, sustained vigilance, without any preconception of what it is that may be found, be it predator or mate, foe or friend.
