'''Nocturne in E minor''', Op. posth. 72, No. 1, was composed by Frédéric Chopin for solo piano in 1827. Chopin's first nocturne, it was the 19th to be published, in 1855. The composition features an unbroken line of quaver triplets in the left hand set against a slow melody of minims, crotchets, quaver duplets and triplets. It consists of 57 bars of common time with the tempo given as ''Andante'', 69 bpm.
File:Chopin Nocturne in Em, Op. posth. 72.ogg
thumb|350px|A secondary theme, in B major.
An informal analysis of the piece is as follows:
*Bar 1: Introduction, First Subject.
*Bar 2-9: Theme A, in E minor.
*Bar 10-17: Variation on theme A, beginning with octaves in the right hand.
*Bar 18-22: Interlude
*Bar 23-30: Theme B, in B major, consisting of a four bar phrase, repeated with variation, Second Subject.
*Bar 31-38: Heavily ornamented variation on A, in E minor, First Subject again.
*Bar 39-46: Variation on theme A, beginning with octaves in the right hand.
*Bar 47-54: Theme B, modulated to E major, Second Subject again.
*Bar 55-57: Coda in E major.
thumb|350px|Second entrance of second theme, in E major.
According to Casimir Wierzyknski, in his book, The Life and Death of Chopin, "[U]p until then this form [the nocturne] had been the exclusive domain of John Field, an Irish-born composer. But his Nocturne in E minor did not satisfy him [Chopin] and was published only posthumously."
This piece was played by the actor Jeri Lynn Zimmermann Ryan while portraying Seven of Nine in the beginning of the Star Trek Voyager episode "Human Error". The piece was also performed by Doc Holiday in the 1993 movie Tombstone (film) and was used as the main theme in The Secret Garden (1987 film).