All compositions studied should be a learning experience, not just memorized. Unfortunately, compositions by the masters are ‘just memorized’ and without the slightest knowledge of what they are made up of. Josef Lhevinne, the legendary pianist of the 20th century, and teacher at the Juilliard school in New York had this to say…read, Also, Dr. Leopold Mannes, founder of the Mannes school of music in New York had this to say…read.
In light of the above, the following is what the Solfeggio is made up of. You won’t find it in any theory manual.
First off is the key signature of three flats; Bb, Eb, and Ab, the first three letters of the word, ‘bead’. This is the key signature for ‘Eb’ major. However, the work is in the ‘relative’ key of ‘C’ minor, the sixth degree of the major scale. The key of ‘C’ minor retains its own identity and ‘relative’ only to its ‘mother’ major scale of its tonic, ‘C’ major.
The first triad in the left hand is a ‘C’ minor triad, arpeggiated. The second triad is a ‘G’ major triad, also arpeggiated, but with the ‘Bb’ of the signature cancelled to ‘B-natural’. The minor 7th, ‘F’ of the dominant (x) is present in the right hand. The right hand scale in the treble of the second measure contains the major 6th ‘A-natural, and major 7th ‘B-natural, of the ‘C’ minor scale the characteristic intervals of the ‘melodic’ minor scale. The characteristic intervals of the ‘normal’ minor scale are the minor 3rd, minor 6th, and minor 7th, taken from its ‘mother’ major scale, ‘C’ major in this case.
 While the key of C minor is ‘relative’ to the key of ‘Eb’ major, minor scales are relative to their own ‘mother’ major scale and retain their own identity. If one were to choose ‘Eb’ major in this case, ‘Bb’ is the 5th note, and Ab the 4th note of the major scale that are cancelled, but these notes have nothing to do with the characteristic intervals of the minor scale.