One of Victorian England's most famous philosophers harbored a secret: Herbert Spencer suffered from an illness so laden with stigma that he feared its revelation would ruin him. He therefore went to extraordinary lengths to hide his malady from the public. Exceptionally, he drew two of his closest friends--the novelist George Eliot and her partner, G. H. Lewes--into his secret. Years later, he also shared it with a remarkable neurologist, John Hughlings-Jackson, better placed than anyone else in England to understand his illness. Spencer insisted that all three support him without betraying...