The plan to write the Mass for the installation ceremonies seems to have been original with Beethoven; it was not suggested by the Archduke or any of his friends, so far as has ever been learned. He began work upon it at once, for Schindler says he saw the beginning of the score in the fall of 1818. Nottebohm’s study of all the sketches which have been discovered (save a number now preserved in the Beethoven House in Bonn which do not add materially to our knowledge) led him to conclusions which may be summed up as follows: The movements were taken up in the order in which the various portions of the text appear in the Roman missal, but work was prosecuted on several movements simultaneously. The _Kyrie_ was begun at the earliest in the middle of 1818, i. e., shortly after the fact of the Archduke’s appointment became known; the _Gloria_ was completely sketched by the end of 1819, the _Credo_ in 1820; the entire Mass was complete in sketch-form in the beginning of 1822. While sketching the Mass Beethoven composed the Pianoforte Sonatas, Op. 109, 110 and 111, the Variations, Op. 107, No. 8, and several other small pieces, including the canons “O, Tobias,” “Gehabt euch wohl,” “Tugend ist kein leerer Name,” and “Gedenkt heute an Baden.” But with the elaboration of the sketches the Mass was not really finished, for subsequently Beethoven undertook many changes. The _Allegro molto_ which enters in the _Credo_ at the words _et ascendit_ is shorter in the autograph than in the printed edition. At the entrance of the words _et iterum_ and _cujus regni_ the autograph is in each case two measures shorter than in the printed score. In the autograph, and also in the copy which Beethoven gave to the Archduke, the trombones do not enter till the words _judicare vivos et mortuos_. There are no trombones in the _Gloria_. The trombone passage which now appears just before the entrance of the chorus on _judicare_ was formerly set for the horns. After the words _et mortuos_ the trombones are silent till the end of the _Credo_ in the autograph; they enter again in the beginning of the _Sanctus_, but are silent at the next _Allegro_. They occur in the _Benedictus_, but are wanting in the _Agnus Dei_. From the nature of these supplementary alterations it is to be concluded that considerable time must have elapsed before they could all be made and the Mass be given the shape in which we know it. Holding to the date on which the copy was delivered to the Archduke (March 19, 1823), the earliest date at which the Mass can have received its definitive shape must be set down as the middle of 1823. Beethoven, therefore, devoted about five years to its composition. He made so many changes in the tympani part of the _Agnus Dei_ that he wore a hole in the very thick paper, his aim being, apparently, by means of a vague rhythm to suggest the distance of the disturbers of the peace. That he was sincere in his purpose to provide a mass for the installation ceremonies is to be found, outside of Schindler’s statement, in a letter to the Archduke written in 1819, in which he says: