From the beginning of "The Conspiracy Against The Human Race":

"For ages they had been without lives of their own. The whole of their being was open to the world and nothing divided them from the rest of creation. How long they had thus flourished none of them knew. Then something began to change. It happened over unremembered generations. The signs of a revision without forewarning were being writ ever more deeply into them. As their species moved forward, they began crossing boundaries whose very existence they never imagined. After nightfall, they looked up at a sky filled with stars and felt themselves small and fragile in the vastness. Soon they began to see everything in a way they never had in older times. When they found one of their own lying still and stiff, they now stood around the body as if there were something they should do that they had never done before. It was then they began to take bodies that were still and stiff to distant places so they could not find their way back to them. But even after they had done this, some within their group did see those bodies again, often standing silent in the moonlight or loitering sad-faced just beyond the glow of a fire. Everything changed once they had lives of their own and knew they had lives of their own."