Book excerpt: "What is the meaning of life?" Throughout history, people have spent much of their lives trying to explain how the world works and why. Initially, they seek to live better lives and thrive. Ultimately, they seek to find purpose and significance in their existence. Experience the scientific and philosophical journey billions of years in the making to answer the question that all living beings capable of rational thought will ask themselves: why are we here? Over the course of that journey, you will come to understand how humans determine their meaning and, with some of your own analysis, discover your own purpose along the way.