The authors warn that their conclusions might be discouraging, because they (convincingly) show that our present predicament was not inevitable—that we could have chosen to make a different world, but didn't. What I found discouraging (or at least bracing) is how the authors show that the task ahead of us—to make a more just world—isn't just about subtracting "civilization" and returning to humanity's supposed egalitarian past. It will involve constructing something new that is contextual and tactical, and that needs constant maintenance.