For all its grace, charm, and apparent simplicity, Chopin's Nocturne in E♭ major, Op. 9, No. 2, poses fundamental problems on close inspection. The fact that so many analyses of the piece – including those of Heinrich Schenker and Felix Salzer – fail to explain certain idiosyncratic aspects, in particular an unusual distribution of structural weight, gives some indication of the Nocturne's complexities at a profound level. Another thorny issue concerns John Field's influence on the work, which could extend beyond foreground features such as figuration to formal and structural characteristics, and which is implicit in Wilhelm von Lenz's comment that “the Nocturne is simply a refined Field, grafted onto a more interesting bass…” A more detailed description of the piece by Lenz – possibly derived from Chopin himself – also casts doubt on the nature of Op. 9, No. 2's construction.

This essay will review the studies of several authors and on the basis of these define a consensus view of the Nocturne's structure. I will then offer an analytical alternative and will consider how the work relates to other early compositions by Chopin, noting similarities which explain its more unusual characteristics, and differences which can perhaps be understood only by comparison with Field's Nocturnes Nos. 1 and 9, both in E♭ major.