Beethoven several times described his Missa solemnis as his greatest work, explaining that it came "from the heart." The surviving sources show us how intensively and how long he worked on the composition in order to give what he felt was adequate expression to the text. Due to its length and musical demands, the Missa solemnis goes far beyond typical liturgical church settings; thus the premiere took place in a concert hall rather than a church. The chorus plays a key structural role in the work and has to master some extremely demanding sections. Leading Beethoven expert Ernst Herttrich has produced an Urtext edition based on the available sources and reflecting the latest state of scholarship.