"The Anatomist" (Ballantine Books, 304 pages, $24.95), by Bill Hayes: Before surgery videos, medical dramas, House and McDreamy laid bare the body's failings, there was a book that showed how each part was supposed to fit together. First published in 1858, "Gray's Anatomy" has never been out of print and become one of the most famous textbooks in the English language. Its detailed anatomical diagrams and descriptions continue to influence artists and medical students today. Bill Hayes used the tome to spell-check anatomical terms for his previous two books exploring sleep disorders and the nature of human blood. "The Anatomist" is Hayes' attempt to reveal the man behind the diagrams, Henry Gray. As Hayes quickly discovers, however, "Gray's Anatomy" is about all that remains of the gifted London medical student who became one of the leading anatomists of his day before his death in 1861 at age 34. None of Gray's manuscripts, letters or journals survive. Hayes' inquiries could have stopped there, were it not for one significant discovery: Though the book bears his name, Gray didn't actually draw any of its 400 diagrams. Those were handiwork of Gray's collaborator, H.V. Carter, whose name was left off some subsequent editions of the book. Luckily for Hayes, Carter did leave behind family letters and journals written in the pinched script of a stressed-out medical student in 19th-century London. Since Gray's body of work is so spare, Hayes makes do with another body: the cadaver in an anatomy class at the University of California-San Francisco. Hayes audits a year's worth of anatomy courses, joining medical students on their first squeamish days with the embalmed corpse through their eventually expert dissections. These had been thinking, dreaming people, Hayes muses over the cadavers. So, too, had been Gray and Carter. Much as the medical students reanimate still-supple joints in the lab, Hayes finds life pulsing in Carter's journals and letters. Through Carter's bleary eyes, Gray emerges as a young man racing to meet the demand for new medical textbooks. Right behind him is Carter, equally seeking knowledge but less sure of his abilities. He can hardly believe the brilliant Gray has asked him to illustrate this new medical text. As in his previous books, Hayes mixes medical history with deceptively light personal observations. He finds the stress of deadlines and dissections has not changed since the 19th century. Nor has the ritual of peeling apart the body, nor the curiosity that draws a crowd to see an organ lifted free from muscle and bone. Hayes stands in for every medical student, every patient, anyone who has ever felt someone else's pulse beneath the skin. "The Anatomist" is as much about Gray and Carter as it is about human connections - fibrous, and otherwise. Learning the origin of the electrical signals that cause the heart to beat, Hayes taps the center of his chest: "Here, right here, is where wonder begins."