This Urtext edition takes into account all the sources, including the old and the new complete editions whose relationship is clearly explained. In several passages, renowned Beethoven specialist Barry Cooper has arrived at variant readings, such as the Sanctus, where the choir enters instead of the soloists, rather than coming in at "Pleni sunct coeli." No less worthy of mention is the addition of the soloists to the choir in most of the Credo. These matters and many other editorial decisions are documented in the detailed critical commentary. This edition is designed for everyone seeking a combination of a reliable musical text and well-founded editorial suggestions for a successful performance of this masterpiece.