Perhaps I'm mistaken, but it seems to me that this Symphony is better than anything I've done so far." Such enthusiasm was rather unusual for the composer, who more often expressed a loathing for his works, but here, it seems, he knew that he had exceeded even his own demanding standards. .
So novel is the sonata-form structure of the first movement that in order to aid its understanding Tchaikovsky uses his introductory, basic motto theme for the purposes of defining his formal outlines and within this framework he develops his unprecedented contrasts. As we know, the conventional "textbook" sonata procedure is based on the tension between the first subject in the tonic key and the contrasting second subject in a related key, normally the dominant. In this symphony Tchaikovsky not only increases the contrasts between the themes and the keys, but also unusually and unconventionally develops thematic and harmonic contrasts. .
The symphony opens with the Fate theme which is a sinister-sounding fanfare in the brass, and this sets the atmosphere of hectic anxiety and fear of an unknown something, which permeates the whole movement. The main body of the movement is marked by the composer "in waltz time" and dotted and syncopated rhythm of the first subject dominates the movement. It is announced at bar 27 first by the strings, then the woodwind, and after the first climax is over Tchaikovsky gives an inverted form of the theme to the basses. After a final fortissimo statement of the theme, the clarinet and bassoon have a short bridge passage, dying away to pianissimo before the clarinet introduces the second subject in A flat minor, instead of the conventional and expect key of A flat major. This is very lightly accompanied by the strings, but when the flutes and oboes adopt this theme the cellos play a cantabile countersubject which finally develops on its own. The key has now modulated to B major (bar 134) which can actually be viewed as C flat major, which is the relative major of the second subject's key of A flat minor, which in turn is the tonic minor of the home key of F major.
