A riveting exploration of how microbes are transforming the way we see nature and ourselves—and could revolutionize agriculture and medicine. Prepare to set aside what you think you know about yourself and microbes. Good health—for people and for plants—depends on Earth’s smallest creatures. The Hidden Half of Nature tells the story of our tangled relationship with microbes and their potential to revolutionize agriculture and medicine, from garden to gut. When David R. Montgomery and Anne Biklé decide to restore life into their barren yard by creating a garden, dead dirt threatens their dream. As a cure, they feed their soil a steady diet of organic matter. The results impress them. In short order, the much-maligned microbes transform their bleak yard into a flourishing Eden. Beneath their feet, beneficial microbes and plant roots continuously exchange a vast array of essential compounds. The authors soon learn that this miniaturized commerce is central to botanical life’s master strategy for defense and health. They are abruptly plunged further into investigating microbes when Biklé is diagnosed with cancer. Here, they discover an unsettling truth. An armada of bacteria (our microbiome) sails the seas of our gut, enabling our immune system to sort microbial friends from foes. But when our gut microbiome goes awry, our health can go with it. The authors also discover startling insights into the similarities between plant roots and the human gut. We are not what we eat. We are all—for better or worse—the product of what our microbes eat. This leads to a radical reconceptualization of our relationship to the natural world: by cultivating beneficial microbes, we can rebuild soil fertility and help turn back the modern plague of chronic diseases. The Hidden Half of Nature reveals how to transform agriculture and medicine—by merging the mind of an ecologist with the care of a gardener and the skill of a doctor.