10. Non troppo allegro, ma agitato – Recitando, rubato

This prelude is an extremely eerie one, perfectly embodying a sense of the grotesque and spectral. While improvisational playing may be an option, it is essential to first recognize the beat and play according to the rhythm (understanding the rhythm) before attempting improvisation. There are not many special precautions to take with this prelude. The piece will almost certainly be completed correctly if you play according to the score's instructions.

Now, let's list other points of caution for this piece.

• Measures 3-6 and 19-23 are the technically challenging sections of this prelude. Practice the octaves so that they can be played accurately without any displacement between the left and right hands. This section requires diligent practice.
• In measures 7-10, hold the whole note ties with the right hand, use no pedal at all, and maintain the staccato in the left hand. In measure 10, count carefully, and since a fermata is applied, this octave G-sharp will be sustained for a considerable duration.
• Measure 11 begins with a ppp so soft that it can barely be heard. This is a truly eerie section; consider the fermata in measure 18 as the goal and gradually build a crescendo towards it.
• In measure 16, beats 1-3, keep the pedal depressed. It is acceptable for the sound to be blurred. The same applies to measures 18, 27, 29, 31, and 34.
• In measure 21, a sixteenth-note triplet begins from the third beat. Although no dynamic markings are written, it would be good to start from pp.
• In measure 23, an unfamiliar marking, 'irato,' is written. Meaning 'with anger,' it should be played extremely roughly and loudly. Therefore, the trill in measure 24 should be played so that the first note, B-sharp, is clearly audible to everyone.
• Measure 38: Pay attention to the count. Be mindful of the triplet speed so that it feels like a triple meter.
• In measure 41, the tonic chord (I) of C-sharp minor must be played so that no one hears it, leaving only the resonance until measure 44 (the final measure). At this point, if you play the left hand at p as indicated, the moment the chord is struck will be noticeable. However, if you play the chord at pp, the sound will not sustain until the final measure and will fade away midway. In this section, play the first note of the left-hand triplet, A, slightly louder to prevent the chord from being detected.