"For the Arkenstone of my father," he said, "is worth more than a river of gold in itself, and to me it is beyond price. That stone of all the treasure I name unto myself, and I will be avenged on anyone who finds it and withholds it."

…shows that Thorin is slipping into madness and can no longer be trusted. That he would threaten capital punishment over a piece of treasure to one of the loyal companions he has led for a year and more is completely out of character…

But he reckoned without the dwarves. The knowledge that the Arkenstone was in the hands of the besiegers burned in their thoughts…

The years lengthened. The embers in the heart of Thorin grew hot again, as he brooded on the wrongs of his house and the vengeance upon the Dragon that he inherited… and a great anger without hope burned him as he smote the red iron on the anvil.

"We have long ago paid the goblins of Moria," said Thorin; "we must give a thought to the Necromancer".

Slowly Aragorn unbuckled his belt and himself set his sword upright against the wall. 'Here I set it,' he said; 'but I command you not to touch it, nor to permit any other to lay hand on it… Death shall come to any man that draws Elendil's sword save Elendil's heir.'

'I only wished to claim the treasure as my very own in those days, and to be rid of the name of thief that was put on me'.

He was hungry too outside, for he was no hunter; but inside the caves he could pick up a living of some sort by stealing food from store or table when no one was at hand.
"I am like a burglar that can't get away, but must go on miserably burgling the same house day after day," he thought.

"… some little return should be made for your, er, hospitality. I mean even a burglar has his feelings. I have drunk much of your wine and eaten much of your bread."

"Well, thief! I smell you and I feel your air. I hear your breath. Come along! Help yourself again, there is plenty and to spare!... You have nice manners for a thief and a liar, …You seem familiar with my name, but I don't seem to remember smelling you before. Who are you and where do you come from, may I ask?"

"Farewell, good thief…"

'It is mine isn’t it? I found it, and Gollum would have killed me, if I hadn't kept it. I'm not a thief, whatever he said.'
'I have never called you one,' Gandalf answered. 'And I am not one either…'

…pursued by his enemy's cries of hate and despair: Thief, thief! Baggins! We hates it for ever!

"As a small token only of your friendship Sauron asks this," he said: "That you should find this thief," such was his word, "and get from him, willing or no, a little ring, the least of rings, that he once stole… Find only news of the thief…"

If thieves came to you, if plunderers came by night — how you have been destroyed! — would they not steal only enough for themselves? [I prefer translating this as: “how did you expect they steal only enough…”] If grape gatherers came to you, would they not leave gleanings? How Esau has been pillaged, his treasures sought out! All your allies have driven you to your border; those at peace with you have deceived you; they have prevailed against you; those who eat your bread have set a trap beneath you — you have no understanding [meaning: without your ever fathoming].

For you yourselves are fully aware that the day of the Lord will come like a thief in the night.

Behold, I am coming like a thief! Blessed is the one who stays awake, keeping his garments on, that he may not go about naked and be seen exposed!

Behold, I send my messenger, and he will prepare the way before me. And the Lord whom you seek will suddenly come to his temple; and the messenger of the covenant in whom you delight, behold, he is coming.

...the ravens brought news that Dain and more than five hundred dwarves, hurrying from the Iron Hills, were now within about two days' march of Dale....
"But they cannot reach the Mountain unmarked," said Roäc, "and I fear lest there be battle in the valley. I do not call this counsel good. Though they are a grim folk, they are not likely to overcome the host that besets you; and even if they did so, what will you gain? Winter and snow is hastening behind them. How shall you be fed without the friendship and goodwill of the lands about you? The treasure is likely to be your death, though the dragon is no more!"
But Thorin was not moved. "Winter and snow will bite both men and elves... ...and they may find their dwelling in the waste grievous to bear. With my friends behind them and winter upon them, they will perhaps be in softer mood to parley with."

No reason to get excited
The thief he kindly spoke
There are many here among us
Who feel that life is but a joke

"Not as stiff as my legs," said Bilbo. "I am tired of stairs and stone passages. I would give a good deal for the feel of grass at my toes."
"I would give a good deal for the feel of a strong drink in my throat, and for a soft bed after a good supper!"
"I can't give you those, while the siege is going on…"

"You are a good fellow, Mr. Baggins, and I will take your offer kindly".

Bombur gave a shiver and a sneeze. 'Stay here a moment' he begged. 'I will fetch another cloak and some wraps, against the Eastwind. There is no need to freeze at one's post.'
No sooner had B. gone than Bilbo slipped on his ring secured his rope slipped over the wall and was gone.
'Confound that hobbit!' said Bombur when he returned. 'What Thorin would say if he knew the watch was broken I don't know.' But in the dark he did not see the rope…

"That was no fish!... There is a spy about. Hide your lights! They will help him more than us, if it is that queer little creature that is said to be their servant."
"Servant, indeed!" snorted Bilbo; and in the middle of his snort he sneezed loudly, and the elves immediately gathered towards the sound.

Well put! I agree that it's as close to a silmaril as we will get in this era of the world.

"I am Mr. Bilbo Baggins... companion of Thorin, if you want to know. I know your king well by sight, though perhaps he doesn't know me to look at. But Bard will remember me, and it is Bard I particularly want to see."
"Indeed!... and what may be your business?"
"Whatever it is, it's my own, my good elves. But if you wish ever to get back to your own woods from this cold cheerless place," he answered shivering, "you will take me along quick to a fire, where I can dry..."

"Really you know," Bilbo was saying in his best business manner, "things are impossible. Personally I am tired of the whole affair. I wish I was back in the West in my own home, where folk are more reasonable..."

"I have an interest in this matter – one fourteenth share, to be precise, according to a letter, which fortunately I believe I have kept."

"If you had dusted the mantelpiece, you would have found this just under the clock," said Gandalf, handing Bilbo a note (written, of course, on his own note-paper).

"Why do you tell us this? Are you betraying your friends, or are you threatening us?" asked Bard grimly. "My dear Bard!" squeaked Bilbo. "Don't be so hasty! I never met such suspicious folk! I am merely trying to avoid trouble for all concerned."

'One who cannot cast away a treasure at need is in fetters.'

The Elvenking himself, whose eyes were used to things of wonder and beauty, stood up in amazement. Even Bard gazed marveling at it in silence. It was as if a globe had been filled with moonlight and hung before them in a net woven of the glint of frosty stars.
"This is the Arkenstone of Thráin... the Heart of the Mountain; and it is also the heart of Thorin. He values it above a river of gold. I give it to you. It will aid you in your bargaining." Then Bilbo, not without a shudder, not without a glance of longing, handed the marvellous stone to Bard.

“the rivers flow with gold”

"But how is it yours to give?" he asked at last with an effort.
"O well!" said the hobbit uncomfortably. "It isn't exactly; but, well, I am willing to let it stand against all my claim... I may be a burglar – or so they say: personally I never really felt like one – but I am an honest one"

"I don't know if it has occurred to you that, even if you could steal the gold bit by bit – a matter of a hundred years or so – you could not get it very far? Not much use of the mountain-side? Not much use in the forest? Bless me! Had you never thought of the catch? A fourteenth share, I suppose or something like it, those were the terms, eh? But what about delivery? What about cartage? What about armed guards and tolls?"…
You will hardly believe it, but poor Bilbo was really very taken aback. So far all his thoughts and energies had been concentrated on getting to the Mountain and finding the entrance. He had never bothered to wonder how the treasure was to be removed, certainly never how any part of it that might fall to his share was to be brought back all the way to Bag-End Under-Hill.
Now a nasty suspicion began to grow in his mind – had the dwarves forgotten this important point too, or were they laughing in their sleeves at him all the time?

Despite the provocative question I threw out at the end of the previous post, I will go on with the obvious identification of Bilbo as the thief described in the chapter’s title

"...Anyway I am going back now, and the dwarves can do what they like to me. I hope you will find it useful."

'And he has been well rewarded, Frodo. Be sure that he took so little hurt from the evil, and escaped in the end, because he began his ownership of the Ring so.'

"He still wandered on… but all the while a very uncomfortable thought was growing inside him. He wondered whether he ought not, now he had the magic ring, to go back into the horrible, horrible, tunnels and look for his friends. He had just made up his mind that it was his duty, that he must turn back-and very miserable he felt about it – "

The Elvenking looked at Bilbo with a new wonder. "Bilbo Baggins... ...You are more worthy to wear the armour of elf-princes than many that have looked more comely in it. But I wonder if Thorin Oakenshield will see it so. I have more knowledge of dwarves in general than you have perhaps. I advise you to remain with us, and here you shall be honoured and thrice welcome."
"Thank you very much I am sure... ...But I don't think I ought to leave my friends like this, after all we have gone through together. And I promised to wake old Bombur at midnight, too! Really I must be going, and quickly."

"For the first time for many a day Bilbo was really delighted."

"All in good time!" said Gandalf. "Things are drawing towards the end now, unless I am mistaken… there is news brewing that even the ravens have not heard. Good night!"

At midnight he woke up Bombur; and then in turn rolled himself up in his corner, without listening to the old dwarf's thanks (which he felt he had hardly earned).

He was soon fast asleep forgetting all his worriers till the morning. As a matter of fact he was dreaming of eggs and bacon.