This week Donald Macleod explores the miraculous chamber music of Mozart's Vienna years. Today, one of the string quartets that caused Haydn to declare Mozart 'the greatest'.

In December 1784, Joseph Haydn, the man considered by many to be the leading composer of the age, escaped the gilded cage of Eszterháza - a mini Versailles set deep in Hungarian marshland, where he was director of music for the opera-mad Prince Nikolaus Eszterházy - to spend the Christmas season amidst the bright lights of Vienna. The following February he was guest of honour at a soirée at his good friend Mozart's swanky new apartments near St Stephen's Cathedral - not any old soirée, but the occasion on which Mozart unveiled three of the six brand new string quartets that would in due course come to be regarded as cornerstones of the Classical repertoire. They quickly became known as his 'Haydn Quartets', in view of the warm and respectful dedication to the older composer that Mozart included in the published edition. We know the dedicatee was impressed, because Mozart's father Leopold, who was visiting Vienna at the time, was also present at the performance, and proudly recorded Haydn's words to him in a letter to his daughter Nannerl: "I say to you before God and as an honest man, your son is the greatest composer known to me in person and by reputation: he has wit and taste and what is more, he has the most thorough knowledge of composition." Included on the programme that evening was Mozart's Quartet in C - the one that's acquired the nickname 'Dissonance', due to the extraordinarily forward-looking harmonies of its slow introduction.

12 Variations in G for piano and violin on 'La Bergère Célimène', K359
Ingrid Haebler (piano)
Henryk Szeryng (violin)

String Quartet in C, K 465 ("Dissonance")
Quatuor Mosaïques. Show less