Haydn's Mass in B flat major (Hob. XXII:12) is generally referred to as the 'Theresienmesse' after the Empress Marie Therese of Austria (1778 –1851). It gets this nickname from the fact that the Empress was an enthusiastic follower of Haydn's music and ordered it to added to her collection once she became aware of its existence. But in fact the nickname is misleading as it wasn't composed for the Empress. It's the fourth in a series of six Masses that Haydn composed for performance at the local Bergkirche between 1796 and 1802 in honour of the birthday of Princess Maria Hermenegild (1768 – 1845) the wife of Haydn's employer Nikolaus II, Prince Esterházy (1765 – 1833). It's a typically Austrian piece of music whose structure and decoration Haydn intended to be the musical equivalent of the stunning interiors found in Central European Baroque and Rococo churches. Coupled to this traditionalism was a desire – entirely typical of the very devout Haydn, to create a joyful and forward-looking piece of music. From my viewpoint he not only succeeded in that aim he also created a piece of music that sounds fresh and vigorous to this day.