In April, 1819, Beethoven"s patron (and pupil) Archduke Rudolph was elected a cardinal, and in June he was further elevated to Archbishop. The date of his formal installation was set for March 9, 1820. As Beethoven’s interest in church music had developed and deepened, he felt that this event presented the perfect occasion to express his appreciation for the Archduke’s benevolence by writing a composition. In a letter to the Archduke, Beethoven wrote, "The day on which a High Mass composed by me will be performed during the ceremonies solemnized for Your Imperial Highness will be the most glorious day of my life; and God will enlighten me so that my poor talents may contribute to the glorification of that solemn day." Beethoven immersed himself in the work completely, devoting his mind and heart to the writing of this Mass. According his biographer Schindler, Beethoven"s personality changed at the beginning of the composition of the Missa Solemnis. Schindler described his state as...