Never Be Sick Again, written by Raymond Francis, M.Sc., explains all disease as really only being one disease with two causes, and six pathways people can take to either stay sick or to never be sick again.
Francis came to this conclusion concerning health after his own health deteriorated to the point in which he was told he there was nothing else that could be done to help him. After bringing his health back using seemingly simple logic and methods Francis has dedicated his energy to help other people understand his theory of disease and health.