The distinguished Hungarian author Frigyes Karinthy was sitting in a Budapest café, wondering whether to write a long-planned monograph on modern man or a new play, when he was disturbed by the roaring—so loud as to drown out all other noises—of a passing train. Soon it was gone, only to be succeeded by another. And another. Strange, Karinthy thought, it had been years since Budapest had streetcars. Only then did he realize he was suffering from an auditory hallucination of extraordinary intensity. What in fact Karinthy was suffering from was a brain tumor, not cancerous but hardly benign, though it was only much later—after spells of giddiness, fainting fits, friends remarking that his handwriting had altered, and books going blank before his eyes—that he consulted a doctor and embarked on a series of examinations that would lead to brain surgery. Karinthy’s description of his descent into illness and his observations of his symptoms, thoughts, and ...