Building on the idea that learning worldly wisdom improves our decisions and our outcomes, volume 2 of The Great Mental Models explains the foundational concepts of physics, chemistry, and biology, demonstrating the value of having these models in your toolkit. These fundamental concepts are everywhere, and if you want to make decisions based on how the world really works, thereby improving your chances of success, then these are critical models to understand. Each chapter explains the key concepts and then explores how to use them as a model by examining historical examples.