The tragedy of our time has been happening all around us, barely noticeable from day to day - the loss of our planet's wild places, its biodiversity. I have been witness to this decline. A Life on Our Planet contains my witness statement, and my vision for the future - the story of how we came to make this, our greatest mistake, and how, if we act now, we can yet put it right. We have the opportunity to create the perfect home for ourselves and restore the wonderful world we inherited. All we need is the will to do so. Sir David Attenborough is Britain's best-known natural history film-maker. His career as a naturalist and broadcaster has spanned nearly seven decades.