Charles Darwin was a sick man for the last forty of his seventy-three years of life. His diaries tell the story of a man deep in the shadow of chronic illness – gnawed at by gastric and intestinal pains, frightened by palpitations, weak and lethargic, often sick and shivery, a bad sleeper, and always an attentive student of his own woes. The diagnoses of organic illness and of neurosis, are not, of course, incompatible. Human beings cannot be straightforwardly ill like cats and mice; almost all chronic illness is surrounded by a penumbra of gloomy imaginings and by worries and fears that may have physical manifestations. The entries in Darwin’s notebooks that bear on his health read to the author like the writings of a man desperately reassuring himself of the reality of his illness.