"There was a war. A Time War. The Last Great Time War. My people fought a race called the Daleks, for the sake of all creation. And they lost. We lost. Everyone lost. They're all gone now. My family. My friends. Even that sky. Oh, you should have seen it! That old planet.... The second sun would rise in the south, and the mountains would shine. The leaves on the trees were silver, when they caught the light, every morning it looked like a forest on fire. When the autumn came, a brilliant glow though the branches..."
— The Doctor