Written by surgeon and renowned author Sherwin B. Nuland, this book offers both a detailed look into the workings of the human body and a glimpse into the heart and work of the author. Furthermore, it is also a philosophical treatise on the wonder of human life and the beauty of "animal economy." As a human biology text for the layman, the book explicates the major organ systems of the human body, such as the nervous system (including the sympathetic nervous system), the cardiovascular system, the gastrointestinal tract, the immunologic and hematologic systems (including coagulation, cell lines, lymphatics), and the urogenital system (including reproduction and childbirth).

Nuland intertwines dramatic stories of his surgical patients with the systems review. For instance, the book begins with the near death of a woman by hemorrhage from a ruptured splenic artery aneurysm. Another dramatic story involves the near death of a young diabetic woman from bacterial overgrowth in the gut. The reader also hears the patients' versions of their illness experiences--Nuland gives direct quotes from what they have said or written about their experiences. Through it all, Nuland expresses his awe and wonder at the workings and capabilities of the human body.