A kind of history of the heart by Dutch cardiologist Dunning, who takes us on a doctor's literary tour of that organ in extreme states. Some of Dunning's tyings together of humanity's involvement with the heart seem forced dilations that allow him to pour and mix his rich research at will. But chapter after chapter holds its own and gathers us into a state of mystical realism. One could hardly expect to find a tie between the burning of Joan of Arc and the hanging of sexual pervert and mass-murderer Gilles de Rais, who were contemporaries. But Joan's heart, it is said by one chronicler, survived her burning, and Gilles's heart was extracted before his hung corpse was placed upon a funeral pyre. Both pyres, Dunning says, ""flare up briefly in the darkness of the Middle Ages [and] represent the outer limits of human conduct."" We follow the birth of the adoration of the Sacred Heart of Jesus through its origins with the French nun Marguerite Marie Alacoque, a religious anorexic who saw Jesus place her heart in his own empty chest--which Dunning ties in with medical investigations of heart disease and heart transplants. His exploration of the diseased heart of Gustav Mahler--weak with streptococcal bacteria--gives Dunning his richest chapter, as he relates Mahler's compositions, his strained love life with Alma Mahler (half his age), and his visit to Freud for an analysis that revealed the source of Mahler's neurotic suffering as an artist: His most sublime melodies were forever being invaded by banal street tunes, a fact that Freud traced back to Mahler's childhood, his abused mother, and a street organ playing ""Ach, du lieber Augustin."" Also discussed: Rembrandt's The Anatomy Lesson, Baudelaire's artificial paradise in absinthe, cannibalism in Poe, and much more. A brilliant unpacking of an extremely overfilled mind.