Haydn's music is, first and foremost, optimistic. It possesses elegance, and incorporates operatic and string quartet elements, but what is most important to understand is that Haydn was a composer full of humor, who loved to surprise people. With this understanding, let us examine the score. At the beginning, you may imagine a string quartet or the voice of a female singer. In any case, heaviness is forbidden; it is crucial to play staccatos as lightly as possible and dotted rhythms lightly. Haydn's unique and delightful surprises, such as sudden fortes, abrupt modulations, and unexpected chords, can be found throughout. For example, the second beat of measure 7 is a V7 chord, which should ideally resolve to the tonic chord in measure 8. However, Haydn has placed a forte marking in the left hand. This can certainly be interpreted as a subito forte. I believe both the right-hand melody and the left-hand accompaniment can be played forte. Measure 16 is clearly a string quartet passage. Imagine strings and play so that the music flows horizontally, while maintaining the polyphonic order. I believe the technically challenging parts of this sonata are the turns. Play the turns that appear throughout without any missing notes or unevenness. Furthermore, attention must be paid to octave passages, such as those in the right hand at measure 42. Treat them melodically and be careful not to play them stiffly. Also, be careful not to overdo the forte markings found in many places. Always maintain elegance. When transitioning from measure 90 to measure 91, although measure 91 becomes octaves, ensure that it does not suddenly become loud. The crescendo begins at measure 86. Gradually increase the volume, aiming for such a smooth entry into measure 91 that the octaves are barely noticed. At measure 105, in the recapitulation, play the melody with a full, robust tone, as if a portly gentleman were singing. Personally, I believe the loudest passage in this movement is between measures 150 and 151. The first left-hand chord in measure 150 can also be played loudly. It is a surprising moment. Many fermatas are found throughout the piece. What the performer must consider is to view this movement as a single story, meticulously contemplating the mood of each fermata and other sections. Imagine what kind of conversation each part represents, what its mood is, and what characters are present. There is no serious discourse. Consider it a truly local, elegant, and optimistic conversation.