A “slender Greek maiden between two Norse giants” was Robert Schumann’s description of the Fourth, a picture that conjures up Classical symmetry and an avoidance of heroic muscle-flexing. What is surprising is not so much that Beethoven broke off work on another symphony to write this one – to fulfil the commission of a wealthy patron, after having written the first two movements of his Fifth – but rather that he must have switched effortlessly from the monumental style of that symphony and the earlier Third and gave his Fourth Symphony a wholly contrasting character. Happiness and humour are often equated with shallowness by devotees of “serious” music, and, in any case, Beethoven’s Fourth lacks the links to a world outside music that back up the two “Norse giants”, so its popularity has always been limited. All the same, even in a basically carefree work like this, Beethoven is not content with a beauty free of conflict but introduces structural peculiarities of extraordinary subtlety; the common ground for all the four movements is a strongly rhythmical motivic base with a wealth of sharply etched chords and staccato figures, which bring out the slenderest lyrical line more strongly than ever. That starts with the dreamy introduction and its hesitant violin figure, continues with the restlessly hurrying Allegro vivace and is audible at once in the Adagio, whose melody needs its pointed cross-rhythm to give it consistency. The scherzo, like almost all of Beethoven’s scherzos, is characterized by a quirk of rhythm and metre which here takes the form of a two-to-the-bar beat in triple time – crushing the beat, as Berlioz put it. And the tearaway string figures of the final movement, here elevated to the status of a main theme, are ultimately unstoppable, either by tutti chords or brief melodious images. This is a symphony of controlled impetuousness.