"'The worthies of Bree will be discussing it a hundred years hence.'
'I hope so,' said Strider. Then they all fell silent, and one by one the hobbits dropped off to sleep."
This first quote is perhaps the most mundane of the three I'm going to mention here. There isn't a whole lot to it. It's two bits of dialog and a sentence of description. However, it manages to hide tone brilliantly. Normally, you don't want to "hide" tone. That should defeat the point. In this specific case, it manages to show a facet of Strider that readers need to see early on. Strider is hopeful, yet still very realistic. Readers who haven't been exposed to the remainder of the story prior to reading this quote may miss some things about it. This statement cements the massive, epic scope of The Lord of the Rings. Strider hopes that "Bree will be discussing it a hundred years hence" because it is quite possible that Bree may be burned to the ground by Sauron within a hundred years. He knows how dire the situation is and if readers read will incredible care they can know too.
At least, that's what I got out of it. Maybe I'm just making that all up...
"There came a cold clear dawn at the end of a long stumbling night-march. The travellers reached a low ridge crowned with ancient holly-trees whose gray-green trunks seemed to have been built out of the very stone of the hills. Their dark leaves shone and their berries glowed red in the light of the rising sun."
In many places I feel that Tolkien's descriptions in LoTR were too extensive. I like bare, Orwellian prose. Here I feel that Papa Tolkien hit a sweet spot. He managed to create an engaging tone, push the plot forward slightly, and show the setting in very few words. These setting details are attractive and manage to give us a sense of the landscape as a whole for this scene, all while playing cool tricks with dawn lighting.
"As soon as Frodo swallowed a little of the warm and fragrant liquor he felt a new strength of heart, and the heavy drowsiness left his limbs. The others also revived and found fresh hope and vigour. But the snow did not relent. It whirled about them thicker than ever, and the wind blew louder."
To my knowledge, the concept of "Yes, but"/"No, and" is relatively modern. This, however, is definitely an old example of its use, on the small scale. Yes, the cordial of Imladris made Frodo feel better, but, the snow made the magic far less useful. Gandalf had a quick fix to their problem, as readers would expect, but natural events managed to thwart it somewhat. Well done, Tolkien.