What is the summary of "The Solitary Reaper" by Wordsworth?

This poem is yet another example of a Wordsworth poem that
is based around one of his walks in nature, but this time in Scotland, rather than in
the ubiquitous Lake District that was the focus of so much of Wordsworth's
poetry.

Whilst walking, Wordsworth comes across a "solitary
Highland Lass" working by herself in the field, reaping and singing. The "melancholy
strain" of her song and the way that it seems to make the vale "overflow" with its sound
causes the speaker to stop and continue his perusal of this solitary reaper without her
being aware of his presence.

The second stanza compares the
sound of the reaper's song to a nightingale's song and then to the cuckoo, finding both
wanting in comparison to the beauty of the reaper's song. The third stanza explores how
the song's meaning cannot be deduced, and the speaker speculates that perhaps it may be
of "old, unhappy, far-off things," or perhaps it captures some "natural sorrow, loss, or
pain" that is eternal.

Either way, the last stanza explores
the way in which the song is sung as if it does not have any ending, and how the
speaker, as he leaves the sight, hears the song in his heart long after he left the
solitary reaper.