Many children’s poems and songs are cumulative – that is, each verse gets progressively longer, usually in a formulaic way: ‘Old McDonald had a farm’, ‘There was an old lady who swallowed a fly’, ‘This is the house that Jack built’, ‘The twelve days of Christmas’, and more seriously, ‘Green grow the rushes, O’. Some theoretically have no ending (‘Old McDonald’), some have an agreed and perhaps rather arbitrary ending ‘The house that Jack built’, ‘The twelve days’ and ‘Green grow’, and some come to a sudden and absurd halt: ‘There was an old lady’ and Rolf Harris’s ‘The court of King Caractacus’.
Even more seriously, Edgar Allen Poe’s ‘The Bells’ has progressively longer lines and progressively longer verses, which made setting it to music quite a challenge. For my setting, I created three- and four- and five-note melodic motifs which I could repeat as necessary.
WS Gilbert’s poem ‘I have a song to sing, O’, set to music by Arthur Sullivan in ‘The Yeoman of the Guard’ is a very subtle example, and repays a close look at how he achieves variation in the way he extends each verse, with prepositional phrases, relative clauses, an adverbial clause of time (I won’t analyse each one in detail), and the humble ‘and’.
He begins: ‘I have a song to sing, O (Sing me your song, O)’. The first two lines of the first verse are one sentence:
It is sung (to the moon) (by a love-lorn loon)
(Who fled) (from the mocking throng-o).
The next four lines are another:
It’s the song (of a merry man moping mum)
(Whose soul was sad) and (whose glance was glum)
(Who sipped no sup) and (who craved no crumb)
(As he sighed) (for the love) (of a lady).
(tl;dr “It’s the song of a man as he sighed”.)
The second verse has four new lines, consisting of two sentences. The first is self-contained and the second might finish, but Gilbert has a twist in his syntax:
It is sung (with the ring) (of the songs) ([that] maids sing)
(Who love) (with a love life-long-o).
It’s a song (of a merry maid peerly proud)
(Who loved a Lord) and (who laughed aloud)
The twist is that Gilbert changes ‘It’s the song of a merry man moping mum’ in the first verse (which would require a new sentence) to ‘At the moan of the merry man moping mum …’ (which therefore continues from the end of the previous line).
The third verse likewise has a new self-contained sentence, followed by another sentence joined to the previous words by a twist to the first line of the previous words:
It is sung (to the knell) (of a church-yard bell)
(And a doleful dirge ding-dong O).
It’s a song (of a popinjay bravely born)
(Who turned up his noble nose) (with scorn)
(At the humble merry maid peerly proud) …
The fourth verse has two twists (and I’ll omit the other bracketing and italicising so that you can see those them):
It is sung with a sigh and with a tear in the eye
For it tells of a righted wrong-o.
It’s a song of the merry maid once so gay
Who turned on her heel and tripped away
From the peacock popinjay bravely born
who turned up his noble nose with scorn
At the humble heart that he did not prize
So she begged on her knees with downcast eyes
For the love of the merry man moping mum
Whose soul was sad and his glance was glum
Who sipped no sup and who craved no crumb
As he sighed for the love of a lady.
The last 10 lines there are all one sentence! (A challenge might be to decide exactly where to put commas!!) Note that Sullivan sometimes repeats whole lines of the melody verbatim, and sometime introduces small variations (and Peter, Paul and Mary introduce more of their own).