This is an interesting thread, in terms of Bilbo's motivation for leaving the Shire for a second time in 3001 TA, this time for good.
According to what he said in Book 1, Chapter I, he first said to Gandalf, just before he left:
'I feel I need a holiday, a very long holiday, as I have told you before. Probably a permanent holiday. I don't expect I shall return. In fact, I don't mean to, and I have made all arrangements.'
He then said he was '
old', though he didn't '
look it'. He was '
beginning to feel it in my heart of hearts'. He felt '
all thin, sort of stretched', like butter scraped over too much bread. He then commented, '
That can't be right. I need a change, or something'.
He said he had made up his mind:
'I want to see mountains again, Gandalf - mountains; and then find somewhere where I can rest. In peace and quiet, without a lot of relatives prying about; and a string of confounded visitors hanging on the bell. I might find somewhere where I can finish my book.'
He also said to Gandalf:
'I want to see the wild country again before I die, and the Mountains; but he [Frodo] is still in love with the Shire, with woods and fields and little rivers'.
In Book 2, Chapter I, when the 4 hobbits got to Rivendall, and Frodo and Sam met Bilbo, the latter said to those two about his travels:
When he had left Hobbiton he wandered off aimlessly, along the Road or in the country on either side; but somehow he had steered all the time towards Rivendell.
He then said:
'I got here without much adventure, and after a rest I went on with the dwarves to Dale: my last journey. I shan't travel again....Then I came back here, and here I have been. I have done this and that. I have written some more of my book. And of course, I make up a few songs. And I listen and I think. Time doesn't seem to pass here: it just is.'
Near the end of
LotR, in Book 6, Chapter VI, 'Many Partings', when the 4 hobbits visited Bilbo in Rivendell, he said that he had returned from his first journey '
by too straight a road'. But he admitted that if he had done so, the auction would have been over; and he would have had '
even more trouble than I did'. He then observed:
'Anyway it's too late now; and really I think it's much more comfortable to sit here and hear about it all. The fire's very cosy here, and the food's very good, and there are Elves when you want them. What more could one want?'
Looking at this, Bilbo's reasons for leaving appear to be:
1. Being very old but not looking old: He was aware that he was a very old hobbit, 111 years old, but certainly didn't look it, something he rightly felt was unnatural. He said to Gandalf that this conflict between how he felt and how he looked made him feel 'stretched'. Also, this was the subject of gossip, people being aware that there was something funny going on without knowing what it was. There was no reason why they should; because Bilbo and Gandalf weren't aware at that time of the Ring's true identity.
2. Peace and quiet: As a result of his age, Bilbo wanted to go somewhere for peace and quiet, without being disturbed by others, and where he would have access to the resources, both living and documentary, to enable him to write. He would also be well looked after, without being an emotional burden on Frodo and other hobbits he cared about. Frodo could also be his own master, in full control of Bag End.
3. To return to old places: Again as a result of his age, he wanted to look again at the places he had been to on his last journey before he died, which he did, going to Dale and the Lonely Mountain before settling in Rivendell. (I have an amusing picture of him being asked to open a new hobbit tea room in Dale or the Mountain!
)