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. In eleven landmark operations, Thomas Morris tells us stories of triumph, reckless bravery, swaggering arrogance, jealousy and rivalry, and incredible ingenuity, from the trail-blazing ‘blue baby’ procedure to the first human heart transplant. The Matter of the Heart gives 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.