In "Energy Transitions," Vaclav Smil delves into the intricate and slow-burning process of how societies shift from one dominant energy source to another, challenging the overly optimistic timelines proposed by contemporary policymakers for moving away from fossil fuels. With his expert analysis, Smil lays bare the historical dependency of human progress on energy sources, from the coal that powered the industrial revolution to the oil that fuels today's global economy. As a world-renowned scientist with an extensive bibliography on energy, Smil provides a sobering reality check on the complexities involved in transitioning to renewable energy. Through a meticulous examination of energy systems, the book not only explores the technical and economic challenges but also the societal changes essential for such a monumental shift. Drawing on a wealth of knowledge, Smil guides readers through the universal patterns of past energy transitions, highlighting how these monumental shifts are intertwined with the evolution of society itself. The book offers a deep dive into the energy landscapes of the world's leading economies, presenting a nuanced understanding of the potential pathways to a sustainable energy future. By comparing specific cases and dissecting the current reliance on fossil fuels, "Energy Transitions" presents a critical analysis of the prospects for a nonfossil world. Smil concludes with a thought-provoking perspective on the nature and pace of the forthcoming shift to renewable energy sources, making this work an indispensable read for anyone interested in the future of energy and society's role in shaping it.