This book explores the fundamental logic behind the growth of various entities, including biological organisms, cities, and nations. It begins by examining how growth impacts living beings, explaining that an organism's metabolism relates to its body mass with a specific mathematical scaling, ultimately limiting its size and lifespan. The text then addresses the underlying theoretical justification for this scaling, introducing the concept of fractals and explaining how certain biological structures, like the circulatory system, exhibit a higher effective dimension due to their pervasive fractal branching. Finally, the book shifts focus to organizational growth in systems like companies and cities, arguing that larger, more complex organizations are more resource-efficient, have higher productivity, and thrive on diversity, making them inherently more robust.