Beethoven's relationship to Archduke Rudolph of Austria (1788–1831) has long played a major role in biographies of the composer and rightly so. He was by far Beethoven's most important patron from 1809 onward. Along with Princes Lobkowitz and Kinsky, he was a signatory to the annuity agreement that persuaded the composer to remain in Vienna, but in the end it was Rudolph alone who fulfilled his financial obligations. Small wonder, then, that Beethoven should dedicate some of his most important works to him, including the Piano Concertos, opp. 58 and 73 (“Emperor”), the Piano Sonata, op. 81a (“Les Adieux”), the Violin Sonata, op. 96, the Piano Trio, op. 97 (“Archduke”), the Piano Sonatas, opp. 106 (“Hammerklavier”) and 111, the Missa solemnis, op. 123, and the Grosse Fuge, op. 133.

The relationship was both deepened and complicated by Rudolph's familial connections to the very center of power at the Habsburg court—he was the youngest brother of the Emperor Franz I—and by the fact that he was also Beethoven's student in composition. Exactly when the archduke's lessons with Beethoven began is unclear, but they brought the two men into close contact repeatedly over a long period of time and made for a considerably more intense association between patron and artist than was normally the case.2 Lewis Lockwood in particular has brought out the multifarious nature of the relationship, both personally and professionally, harmonious at times, dissonant at others.

From the middle of the nineteenth century onward, however, most critics have tended to idealize the relationship between the two, in no small part because it offers the attractive image of a royal personage and a bourgeois subject engaged in a common endeavor: the craft of musical art. The surviving correspondence, along with certain particulars of the Piano Sonata, op. 81a, and of the Missa solemnis, have helped elevate the perception of the relationship to the level of friendship and even, in the eyes of some, deep affection.