The librettist borrows from Longfellow's translation of the ballad Der schwarze Ritter by Ludwig Uhland.
Elgar was motivated to complete work on The Black Knight when offered a performance at the Worcester Festival.
Basil Maine, a leading Elgar biographer, believes the purpose of the work is to create a close mix of vocal and instrumental tones.
[1] Elgar's The Black Knight tells the story of the intrusion of a mysterious stranger into a king's court with disastrous and gruesome result.
It starts with a medieval jousting competition held in honor of the feast of Pentecost: in the competition, the king's son beats everyone in the lists until a mysterious knight arrives and challenges him, and with the sky darkening and the castle rocking, the strange knight fights and wins.
Later, noticing the paleness of the king's two children, the guest offers 'healing' wine to them, who collapse and die soon after drinking the poison.
Music writer Diana McVeagh observes that there seems to be no moral cause or explanation for the gratuitous evil of the stranger.
During the knight's dance with the king's daughter, his theme becomes chaotic: for example, the orchestra replays the original diminished seventh again as the flower in her hair died.