By 1822, Beethoven was becoming ever more reclusive and his behaviour increasingly strange. After an unproductive few years, thanks to a long drawn out guardianship battle over his nephew Carl, he'd finally found his feet again. His last piano sonata dates from that year as does the Handelian overture The Consecration of the House. But his greatest project, which took some five years to complete, was the Missa Solemnis, his largest choral work and for Beethoven, the supreme challenge of his life. Donald Macleod explores key music and events of Beethoven's year.