This book argues that the West is in economic decline due to three interrelated factors, described as the Guns-Oil-Oligarchy nexus. This chapter defines fundamental concepts featured in the rest of the book, and the historical context of the West’s economic rise is discussed as a necessary background. This includes the Industrial Revolution and the Great Acceleration, which were marked by accelerating economic growth. This discussion foreshadows the discussion in Chap. 2 on how the West has fallen into a Growth Trap that has caused ecological overshoot and socio-political instability. The Growth Trap is shown to have two salient features that form the cores of Chaps. 3–5: the concentration of economic power in the hands of oligarchs, the world’s dependence on oil, and the rise of the military-industrial complex. This book shows why the Guns-Oil-Oligarchy is a simple explanation for the West’s economic decline, and how its understanding offers a simple solution to avert further economic decline: the oligarchs’ grip must be broken.