In derivation and general significance the term nocturne coincides with
our English word nocturnal. It is music appertaining to the night, a
night piece, suited to and expressing its usually quiet, dreamful,
pensive mood, and frequently portraying some nocturnal scene or episode.
The name nocturne was originally used as synonymous with that of
serenade, and they were virtually identical in character. But in later
times it has come to have a much broader application, and to-day, though
every serenade is of course a nocturne, all nocturnes are by no means
serenades.
The serenade is a real or imaginary song of love, and presupposes a fair
listener at a lattice window and a lover singing beneath the stars, to
the accompaniment of a harp, mandolin, or guitar. The nocturne may
legitimately embody any phase of human emotion or experience, or any
aspect of inanimate nature, which can rationally be conceived of as
appropriately emanating from or environed by nocturnal conditions.
It must not be supposed that this vein of composition was Chopin’s only
or even his most important field of activity. To judge him exclusively
by his nocturnes and waltzes is precisely like judging Shakespeare
solely by his sonnets. But it was a vein in which, owing to his
peculiarly poetic temperament and fertile imagination, he far excelled
all other writers, no less in the quality than in the number and variety
of his creations.