Much of the credit for the formation and organization of the rules of counterpoint is given to a single man by the name of Joseph Fux. His classic and groundbreaking work on counterpoint, Gradus ad parnassum, is regarded as the most important contribution to the advancement of the theories of counterpoint. It has been historically proven that great composers such as Haydn, Mozart, as well as Beethoven worked from the same book (giving much to say concerning the usefulness and importance of this method.)