Beethoven didn’t attach “Moonlight” to this first movement of his very popular C# minor Sonata. (Music critics often invented these tags that stuck over centuries) The composer, himself, said his opening was like a fantasy, “quasi una fantasia,” and he took particular care to compose his Adagio Sustenuto movement in alla breve, which meant that each measure should be played in two, not four. (Think of two groups of triplets, as taking up the space of one beat, and then another pair of triplets comprising the second beat)
How I approach the composition when learning it from the ground up:
Start by playing every chord in the key of C# minor using the Harmonic Form (raise B to B#)
Listen for the quality of each chord: Major, Minor, Augmented, Diminished
Identify the Neapolitan chord in this Key:
Lower the second degree by a half step to D, and build a Major Chord on it. (D Major, D F# A)
Practice playing the Neapolitan (D F# A) to the Dominant (G# B# D#) to tonic, (C# E G#)
Invert these chords for smoother, easier voice leading between them. A characteristic of Beethoven’s first movement, is the smooth passage of broken chords from one to another though chord inversions.
Layered Learning: (There are more practice steps indicated here than in the video)
1)Isolate and block out chords for each triplet from the beginning to the end of piece. You can use pedal. (GOOD FINGERING IS A MUST!) Use a supple wrist, and play with a nice flow from chord to chord. Think in big groups of TWO right from the start.
Try to name the chords and their function, whether Major, minor, or diminished, etc. and if, tonic, Sub Dominant, Dominant etc.
Look for SECONDARY DOMINANTS where there are MODULATIONS to other keys besides C# minor. Identify the KEY CHANGES and how they occurred. (Notice the voice leading between chords–what notes remain the same–which ones move away–and then come back or not, etc)
2) Isolate the Bass line, and think again of underlying groups of TWO beats to each measure.
3) Play the bass line (Left Hand) and the block chords above (Right Hand)
4) Isolate the Melody (This can be tricky since fingering has to synchronize well with the alto voice below with the broken chords)
USE A GOOD FINGERING FOR THE TOP OR SOPRANO LINE.
6) Play the soprano line with the bass line.
7) Play the soprano line with block chords in the alto voice (Create a nice balance–with melody resonating over chords)
8) Play the bass, alto chords, soprano line all together (Be aware of voice balance–ring out the melody)
8) Finally Play All Parts as written. Think again in groups of TWO for each measure. (Balance awareness, once again, between soprano, alto and bass)
BACK TEMPO is always a good idea. Gradually bring the movement into tempo when ready. A piece ripens with time.
PEDALING: BE GUIDED BY THE HARMONIC RHYTHM, or changes in Harmony.
Various esteemed pianists, perform this movement at different tempi.
Check Murray Perahia, Wilhelm Kempff, Vladimir Horowitz, Daniel Barenboim as reference on You Tube.