If this book has a lesson, it is that we are awfully lucky to be here - and by 'we' I mean every living thing. To attain any kind of life at all in this universe of ours appears to be quite an achievement. As humans we are doubly lucky, of course. We enjoy not only the privilege of existence, but also the singular ability to appreciate it and even, in a multitude of ways, to make it better. It is a trick we have only just begun to grasp.