As I read it, all we need to do to make the logic of Bilbo's sentence obvious is to add one comma:
"But, all the while I sit and think of times there were before, I listen ..."
I read "but" as belonging to the independent clause rather than the dependent clause. The bit of syntactical confusion here is caused by the omission of the comma after "but," which would bookend the parenthetical "all the while I sit and think of times there were before." Logically, the clause should be set off by a pair of commas, not a single comma.
It's common for writers to omit the first comma of a parenthetical phrase/clause in this situation, where it would follow a short conjunction that begins the sentence. Including the comma would make the sentence sound stilted. And, when we're reading at a normal pace (rather than parsing the sentence), we are more likely to become confused if the comma is included than if it is absent. Especially if the parenthetical is long and complex, as in Bilbo's poem—and the previous sentence. ;-)
At least, that is what I tell myself when I come across one of these as an editor and it makes my ears tingle.
My apologies if I'm repeating an observation someone has already made; I haven't had time to read all the discussion about this!
"But, all the while I sit and think of times there were before, I listen ..."
I read "but" as belonging to the independent clause rather than the dependent clause. The bit of syntactical confusion here is caused by the omission of the comma after "but," which would bookend the parenthetical "all the while I sit and think of times there were before." Logically, the clause should be set off by a pair of commas, not a single comma.
It's common for writers to omit the first comma of a parenthetical phrase/clause in this situation, where it would follow a short conjunction that begins the sentence. Including the comma would make the sentence sound stilted. And, when we're reading at a normal pace (rather than parsing the sentence), we are more likely to become confused if the comma is included than if it is absent. Especially if the parenthetical is long and complex, as in Bilbo's poem—and the previous sentence. ;-)
At least, that is what I tell myself when I come across one of these as an editor and it makes my ears tingle.
My apologies if I'm repeating an observation someone has already made; I haven't had time to read all the discussion about this!