For thousands of years the human heart remained the deepest of mysteries; both home to the soul and an organ too complex to touch, let alone operate on.Then, in the late nineteenth century, medics began going where no one had dared go before. The following decades saw the mysteries of the heart exposed, thanks to pioneering surgeons, brave patients and even sacrificial dogs. In 11 landmark operations, Thomas Morris tells us stories of triumph, reckless bravery, swaggering arrogance, jealousy and rivalry, and incredible ingenuity- the trail-blazing 'blue baby' procedure that transformed wheezing infants into pink, healthy children; the first human heart transplant, which made headline news around the globe. And yet the heart still feels sacred- just before the operation to fit one of the first artificial hearts, the patient's wife asked the surgeon if he would still be able to love her. The Matter of the Heartgives us a view over the surgeon's shoulder, showing us the heart's inner workings and failings. It describes both a human story and a history of risk-taking that has ultimately saved millions of lives.