As an idealist, Graham was drawn to the history of the Jesuit missions in Paraguay -- a period known as one of the golden ages of mankind. Protecting their Guarani Indian charges from slave raids from both the Spanish and the Portuguese, the missionaries built up a civilization isolated from the rest of the world and protected it fairly successfully for a century and a half until a Spanish fellow enforced the expulsion of the Jesuit order from South America. The film "The Mission" was loosely based on Graham's book and, although it took liberties with the story, was basically sympathetic to the author's feeling for the Jesuits and their Indian charges.