While cells are commonly considered the building block of living things, it is actually the communication between cells that brings us to life, controlling our bodies and brains, determining whether we are healthy or sick, and directly influencing how we think, feel, and behave. In , doctor and neuroscientist Jon Lieff lets us listen in on these conversations, and reveals their significance for everything from mental health to cancer. He explains the surprising science of how very different cells—bacteria and brain cells, blood cells and viruses—all speak the same language. This overarching principle has been long overlooked because scientific journals use impenetrable jargon that makes it hard to be understood across disciplines, much less by the general public. Lieff presents a fascinating and accessible look into cellular communication science—a groundbreaking and comprehensive exploration of this biological phenomenon. In these pages, discover the intriguing lives of cells as they ask questions, get answers, give feedback, gather information, call for each other, and make complex decisions. During infections, immune T-cells tell brain cells that we should "feel sick" and lie down. Cancer cells warn their community about immune and microbe attacks. Gut cells talk with microbes to determine which are friends and which are enemies, and microbes talk with each other and with much more complicated human cells in ways that determine which medicines work and which will fail. With applications for immunity, chronic pain, weight loss, depression, cancer treatment, and virtually every aspect of health and biology, cellular communication is revolutionizing our understanding not just of disease, but of life itself. is required reading for anyone interested in following the conversation.