Over time Wolfgang Amadeus Mozart‘s “Missa in C major” K. 257 has been given many nicknames. This work, also known as the “Great Credo Mass” was referred to as “Missa longa” by Leopold Mozart due to its duration. Mozart usually liked to call works of this magnitude “Missa solemnis“, but for unknown reasons, in the case of the “Great Credo Mass”, he did not use this title. As the work was originally composed for the ordination of Salzburg Canon Ignaz von Spaur, Leopold also called the work “Spaur Mass”.
The mass was composed in late 1776 or early 1777 in the usual baroque tradition where the three trombones are set Tutti colla parte with the alto, tenor and bass parts.
The spatial separation of singers in the Salzburg Cathedral is somewhat similar to the polychoral style, in which solo and choir ensemble performed separately with one organ each. The soloists along with the first organ formed the “concerto”, while the choir and the second organ took on the “ripieno” role.
Walter Senn’s edition is largely based on the autograph score, as well as on a set of autograph parts that was added and corrected by Wolfgang Amadeus and Leopold Mozart at a later time.