The introductory chapter sets forth the book’s central argument that the struggle over inequality has been the underlying force driving the unfolding of all human history. This struggle underlies the other presumed primary drivers of history such as technological advances, demographics, group conflict, war, religion, or great men. Three key supporting claims are briefly explored. First, the ultimate driving force for inequality is found in human biology, the fact that the decisive competition that counts for sexually reproducing animal species is success in mating and thereby sending one’s unique set of genes into future generations. Second, because of sexual selection and because humans are social beings, inequality underlies all politics. Third, although physical violence always remains the trump card in creating, maintaining, or increasing inequality, ideology has always been, day to day, the most important inequality-sustaining political weapon. How the book will unfold is then set forth.