This dissertation considers Haydn's music for theater as a unique phenomenon staying apart from usual theatrical aesthetic criteria. Being created within the specific festive atmosphere of the private theaters of Eszterhaza, Haydn's operas live by their own rules which affect both their general appearance and particular details.
The libretti and music of the Italian and German operas were analyzed with special attention paid to the unusual traits repeating from opera to opera. Almost all the libretti have some qualities normally regarded as dramatic failures: too long action, unnecessary third acts, softened culminations, lack of drama. But these "failures", when articulated musically, appear quite logical. It is obvious that the text allows some time and space for the audience's perception and understanding of the music. One finds elaborate motive-work, thematic connections between separate numbers, the theme of the overture reappearing in music that follows later on, a specific meaning of certain keys in the operas, which certainly should be regarded as signs of symphonic procedure in opera, but a symphonic procedure in a sense specific to Haydn.
Haydn had an intrinsic quality of symphonic thinking which naturally appeared in all his music. Opera was no exception, and developing patterns and techniques typical for instrumental music began to be used in it. This idea was a very promising one and its development led up to modern opera.