Definitions are the basis of understanding the language of music, and without complete definitions of musical terms there is no such thing as musical understanding that is meaningful. ‘Harmonic Identity’ is the first definition, with ‘harmonic function next. Please note the hierarchy of analysis in the line below; chord names; their roots above the staves as F, Eb, Ab etc., then chord identities between the staves; m, x, M, m, etc., and chord functions below the staves; I, VII, III, V, etc.
Note that VII is a normal dominant (x), and V is an altered dominant. If V were major it could be indicated as ‘VM’, a major chord on the dominant. However, the chord is a dominant on this dominant. And here we begin to see the word ‘dominant’ as having two different meanings; one as a function (V), and the other as an identity, and ‘V7’ (dominant-seventh) is not the identity of ‘V’, the dominant. And, if VII is a dominant but not on the fifth note of the scale, then is it a ‘secondary dominant’? …’V7/III’? Then, where will this ‘identifier’ be put… in the ‘identity’ line between the staves, ‘m –V7/III-M-x’, or in the ‘function’ line below the staves, ‘I-V7/III-V’ and if this is the option, what happens to the function of the chord as the sub-dominant, ‘VI’? I think you may be able to see the convoluted theory that is being promoted in all theory texts. In addition, the ear should be able to recognize ‘D-flat’ as the minor 7th of this dominant, and ‘G’, the major 3rd, the lower-most note in the bass. These intervals are the characteristic intervals of the dominant (x), and not ‘V7/III’.
Recognizing chords by their identity is vital. The first chord is an ‘F’ chord, but it is also a minor chord, with its characteristic interval of a minor 3rd; ‘A-flat’. Each chord must be heard for what it is; its identity. The second chord is an ‘E-flat’ chord, but also a dominant (x) with the bass, ‘G’ as the major 3rd, and the melodic ‘D-flat’ as the minor 7th. Note that the harmonic ‘rhythm’ is in half-notes, two beats make up the whole chord, not just one beat.
Merely memorizing and practicing notes without an understanding of what the music is made up of is referred to as ‘parroting’…mindless practice.
If you wish to have the analysis of the complete Nocturne, e-mail me for the e-book.
Ralph Carroll Hedges, B.Ed., B.Mus., M.M.
 ‘Identity’ may be defined as the item itself without reference to a function. A major chord for example is a major chord with its characteristic interval(s) without regard to a key signature, and may be found any place one wishes to use it. A ‘function’ on the other hand is a position and is expressed with a number; Arabic 1, 2, 3, etc. or Roman I, II, III, etc. It has become a fad to use lower case Roman numerals to express minor; ii. Please don’t, it’s far too inconsistent and cumbersome. Refer to the article, “Compound Symbols” by the author.
 For some inexplicable reason theorists, publishers, and theory texts do not allow an identifier for the dominant, while a few writers use ‘x’ but without explanation. ‘x’ as a dominant identifier does not conflict with any other symbol, so is used here. And, by using this symbol music theory may take on a far more logical sense with the theory of ‘secondary dominants’ dispensable.
 The use of ‘figured bass’ for the ‘first inversion’ of the dominant on the VII chord; 6/5 is also convoluted, since neither of these numbers represent the 3rd as the lower-most note, nor do they represent the characteristic intervals of the chord. Drawing a line under either the identity or the function with ‘3’, or ‘M3’ for the ‘G’ in the bass will be far more direct, logical, and far less confusing. Figured bass was developed during the Baroque period and is for the Baroque specialist in ‘realizing’ an accompaniment for the keyboardist in a Baroque orchestra, not for ‘you and me’. But theorists love to use and teach it but for no good reason.