The grandeur of Mozart's Missa solemnis in C minor 'Waisenhausmesse' caused Viennese scholars to doubt how it could have been composed by a twelve-year old boy. The Mass was written for the consecration of a new Orphanage Church in Vienna with an expanded orchestra, and it's premiere was conducted by Mozart himself 'to the general approbation and admiration of everyone'. Mozart often made use of the purity of C major in his Masses - the Missa brevis is a remarkable model of compactness, while the Missa solemnis is Mozart's last complete Mass.
