The Professor and The Madman by Simon Winchester was originally published under the title The Surgeon of Crowthorne: A Tale of Murder, Madness and the Love of Words in 1998, in England, and was retitled when released in the United States. A film was made of the book under the title The Professor and The Madman. The work described the interactions between the madman of the title, Dr. William C. Minor (a doctor incarcerated in a hospital for the criminally insane), and the scholar in charge of the creation of the Oxford English Dictionary: James Augustus Henry Murray.
The first major theme of the work is the nature of madness. While Minor was clearly delusional and paranoid, with bizarre sexual and persecution fantasies (which led to his murdering an innocent person), he nonetheless was a careful, balanced, and objective researcher. This suggests that "madness" is not some overarching category that makes all aspects of someone's thought unreliable—just because Minor is considered "mad," this does not negate his potential to contribute to meaningful research (and perhaps to society as a whole).
A second major theme is the treatment of madness. The regime at Broadmoor which allowed wealthy inmates to have servants and live relatively normal lives permitted Minor to make a positive contribution to society while incarcerated. This makes readers consider that "treatment" for madness perhaps should not so much focus on a "cure" but rather on helping people live productive lives with a chronic mental illness.
Finally, and especially important now we live in an age of electronically mediated communication, this shows how lack of knowledge of another person might actually be positive. By initially not knowing the identity of Minor, Murray could develop a productive relationship with him without stigma or prejudice. This suggests that some of the problems encountered by the mentally ill and their difficulty finding employment are due to prejudice and that this book helps readers move beyond such prejudice.