At the end of this 21st Century, humans will number 11 billion, so numerous that our planet will be unable to sustain them. Then, as must be the case for any animal species that grows beyond the limited resources of its environment, Earth’s population will have to decrease. In a few centuries, it will eventually settle around 200 million, a level that, long ago, had prevailed for millennia. The rapid growth of the human population followed by its collapse, will be but a small parenthesis in the geological time frame. This return to the natural equilibrium will come about over a stretch of time long enough for our species to adapt and will not be the result of a catastrophic event. On the contrary, all available signs indicate that we are witnessing the beginning of a revolution that will remodel human civilization and increase its happiness. This book explains the reasons for this and expounds on the political, economic and social consequences for the coming decades.