There seem to be two periods--one from 1808 to 1811, during his love affair with Therese Malfatti, and again after his brother’s death in 1815--when outward circumstances prevailed against the artist and rendered him comparatively silent. Unable to loosen the grip of personal emotion, during these periods he wrote little of importance. ‘During all the rest of his agitated and tormented life nothing, neither the constant series of passionate and brief loves, nor constant bodily sickness, trouble about money, trouble about friends, relations, and the unspeakable nephew, meant anything vital to his deeper self. The nephew helped to kill him, but could not color a note of his music.’[57] If, as in the case of the ‘Eroica,’ music was sometimes the reflection of present emotion, it was still oftener, as in the case just cited, his magic against it, his shelter from grief, the rock-wall with which he shut out the woes of life. V In the development of his artistic career three circumstances may be counted as strongly determining factors: his early experience in the theatre at Bonn, his skill on the pianoforte, and his lifelong preference for the sonata form. In regard to the first, it is clearly evident that, although Beethoven was moved least of all by operatic works, yet his constant familiarity with the orchestra during the formative years of his life must have left a strong impression. From 1788 to 1792 at the National Theatre in Bonn he was playing in such works as _Die Entführung_, _Don Giovanni_, and _Figaro_ by Mozart, _Die Pilgrime von Mekka_ by Gluck, and productions by Salieri, Benda, Dittersdorf, and Paesiello. That in after life he wrote but one opera was probably due to a number of causes, one of which was his difficulty in finding a libretto to his liking. His diary and letters show that he was frequently in correspondence with various poets concerning a libretto, and that the purpose of further operatic work was never dismissed from his mind. But he always conceived his melodies and musical ideas instrumentally rather than vocally, and never was able or willing to modify them to suit the compass of the average voice. One consequence of this was that he had endless trouble and difficulty in the production of his opera, _Fidelio_, which was withdrawn after the first three performances. Upon its revival it was played to larger and more appreciative audiences, but was again suddenly and finally withdrawn by the composer after a quarrel with Baron von Braun, the intendant of the theatre.