“the Earendil poem chanted by Bilbo in Rivendell the night before the Council of Elrond”
“it had started as a completely different piece (as far as subject matter went), called ‘Errantry’. Around 1930 or 1931, Tolkien composed the poem with a meter and rhyme scheme so difficult it makes the Earendil poem seem like iambic verse”
“Tolkien referred to it in a 1966 letter as “a piece of verbal acrobatics and metrical high-jinks… intended for recitation with great variations of speed.””
“The poem had many, many revisions, which are all well documented in The Treason of Isengard by Christopher Tolkien. For its inclusion in the Lord of the Rings, Tolkien reworked “Errantry,” created fifteen or so different drafts which spanned the spectrum from the original to the Earendil poem”
“A few years after Lord of the Rings, when Tolkien wished to include ‘Errantry’ in his Adventures of Tom Bombadil collection, he came up with a bit of retcon, as he was wont to do”
“The poem, “Errantry,” was “evidently made by Bilbo. This is indicated by its obvious relationship to the long poem recited by Bilbo, as his own composition, in the house of Elrond.” And so Tolkien projected his own writing history upon Bilbo.
“Probably because Bilbo invented its metrical devices and was proud of them. They do not appear in other pieces in the Red Book. The older form, here given, must belong to the early days after Bilbo’s return from his journey.””
“to use Tolkien’s own words from a 1952 letter (No. 133): “It is for one thing in a metre I invented (depending on trisyllabic assonances or near-assonances) , which is so difficult that except in this one example I have never been able to use it again – it just blew out in a single impulse.””