His Magnum Opus was a sequence of almost 100 novels and plays collectively entitled La Comedie Humaine, which presents a panorama of French life in the years after the fall of Napoleon Bonaparte in 1815. Due to his keen observation of detail and unfiltered representation of society, Balzac is regarded as one of the founders of realism in European literature. He is renowned for his multi-faceted characters; even his lesser characters are complex, morally ambiguous and fully human. Inanimate objects are imbued with character as well; the city of Paris, a backdrop for much of his writing, takes on many human qualities. His writing influenced many famous authors, including the novelists Marcel Proust, Emile Zola, Charles Dickens, Gustave Flaubert, Marie Corelli, Henry James and Jack Kerouac, as well as important philosophers such as Friedrich Engels. Many of Balzac's works have been made into films, and they continue to inspire other writers.

    Most of the guides are devoted to a single opera, which is described in detail—with many articles that cover its history and information about the composer and his times. The complete libretto is included in both the original language and in a modern singing translation—except where the opera was written in English. Each has a thematic guide to the most important musical themes in musical notation and each guide is lavishly illustrated. They also contain a bibliography and a discography which is updated at each reprint. The ENO guides are widely regarded as the best series of their kind and excellent value.