Vaclav Smil explains the fundamental material realities underlying modern civilization, from the energy systems that power our world to the food production that sustains eight billion people. Writing with the authority of a scientist who has spent decades studying how the world actually works, Smil cuts through both techno-optimism and doom-mongering to explain what science and technology can and cannot accomplish. He examines the essential materials of modern life, steel, concrete, plastics, and ammonia, showing how dependent we remain on fossil fuels for their production despite renewable energy's growth. Smil analyzes food systems from farm to table, revealing the energy inputs required to feed humanity and the challenges of transforming agriculture. He addresses globalization's material foundations, the actual risks we face versus those we fear, and the gap between aspirational goals and physical realities. Throughout, Smil emphasizes that understanding the world requires quantitative thinking and respect for material constraints that wishful thinking cannot overcome. His approach is neither optimistic nor pessimistic but rigorously empirical, grounding discussions of climate change, energy transition, and technological progress in physical reality. The book challenges readers to think more clearly about the trade-offs inherent in any path forward, providing essential context for citizens navigating complex decisions about technology, environment, and society.