How linear algebra structures the universe and shapes our brain's perception of reality. Why do distant mountains look tiny while your coffee mug looms large? How does your brain find its way in a dark room? And what does any of this have to do with quantum physics? In The Power of Lines , Oscar Fernandez traces the answers to one startling conclusion: the universe runs on linear algebra. Fernandez builds his case by uncovering the hidden linearity all around us, from simple activities--like making coffee and searching the Web--to the complex systems that shape society, like social networks and global markets. Along the way, he shows how the same mathematical ideas--linear equations, matrices, transformations--quietly power them all. And in a finale that redefines "mind-blowing," he reveals that your brain, too, relies on this same mathematics to make sense of reality. Clear, vivid, and complemented with key calculations in the chapter appendices, The Power of Lines is a guided tour of the mathematics that explains everything from quantum physics to perception. After reading it, you'll never see the world--or your mind--the same way again.