While many of Haydn's sonatas are optimistic in nature, it is rare to find a piece where Haydn's sense of humor is as fully expressed as in the first movement of this sonata. Observing the choreography of playing the opening measures of this sonata makes it immediately clear: just as a cat moves its left and right paws alternately, the human hands also play alternately from left to right, which alone creates a considerably joyful atmosphere.

In any case, this first movement is filled with unexpected jokes scattered throughout, expressing 'surprise' and 'laughter'. For example, the G in the left-hand octave on the third beat of measure 21, being part of the theme, should ideally be written as an eighth note, yet for some reason, it is written as a quarter note. This seems to be a playful tease. Furthermore, the unit of four sixteenth notes plus an eighth note, starting from measure 90, jumps around in pitch, alternating between pp and forte. This section is where jokes are played to surprise or tease, and finally, the cadenza in measures 99-100 can be understood as an expression of 'hahaha' laughter.

Thus, in this first movement, full of joy, the point of caution is the tempo, which is the most common mistake people make. That is, the tempo tends to change depending on the section. In extreme cases, because sixteenth notes appear in measure 10, the tempo already changes there. Even in sections with fast notes, such as measures 44-45, please maintain the same tempo as measure 1. Of course, you may also adjust measure 1 to match these sections.

The next example, which also applies to the cadenza of Beethoven's 'Tempest' Sonata, first movement, concerns measures 72-73, where 'open pedal' is indicated. However, please remember that this is merely a marking for instruments of that era. If you were to do the same on a modern piano, it would create muddiness. Please try to adjust the pedal appropriately, perhaps by using half-pedaling.

In measure 32, for the left-hand third between the 3rd and 4th beats, take the right-hand E-G on the 3rd beat with fingers 3 and 5 of the right hand, and take the notes G-A-H-C above the third with the right hand. If you can play the left-hand third without difficulty, there is no need to do this. In measure 109, the left hand is difficult. Please take the last note of the left hand with the right hand. Similarly, the same applies to the left hand on the 3rd beat; take the last note with the right hand.