I'm going to use this first post to look back from Pippin's encounter in the Stone of Orthanc over the story we have read, going all the way back to Bag-end, and trying to bring the TT themes and elements into a wider focus. You'all should feel free to discuss anything pertaining to the story that you wish!A wrap-up sounds great to me.
(1) Bag-end to Rivendell
When Tolkien sat down to write a sequel to The Hobbit he began with another party, connected the magic ring with Sauron the Necromancer, and then began a story intended to follow the road of the adventure of Bilbo Baggins - to Rivendell, only with the main part of the adventures happening off-road before (rather than after) the Last Homely House; the basic idea, then, was some adventures in the realm of Tom Bombadil. This is the main spirit of the first book, but already before leaving the Shire an encounter with a Black Rider points to some turbulence ahead - here is one who has already 'passed through' another evil magic ring! After leaving Bree, in the company now of a strange Ranger, the terrible encounter on Weathertop spells out all too clearly the peril and the menace of this evil Ring of Power.
2. Rivendell
Now Tolkien gets his full story together, histories and meanings only hinted at in 'The Shadow of the Past' are set down in concise significance, the nature of the quest - to destroy the One Ring - is settled, and the Fellowship of the Ring is born.
3. Moria
This is the turning point of the story. On the western gate is the star of Fëanor and the signs of the High Elves of Eregion - the details from Gandalf's talk in Bag-end in the second chapter are getting threshed out: here on the door - to those who see - is the name of Celebrimbor - grandson of Fëanor, he who made the Rings of Power in the Second Age. At the great Council in Rivendell we learned (just) enough of the great second age story of mortals: the Fall of Numenor, and now at the Doors of Durin we learn (just) enough to know the elf and dwarf Second Age stories: and in all, or at least both mortal and elf, is the same story: Sauron was then fair and received as a friend - and deceived: Numenor fell and Frodo Baggins bears around his neck the price a later age of the world must pay for the folly of the Elf-craftsmen of Hollin. And awaiting beyond the door is a Balrog.
4. Lothlórien
Beyond the mountains, and now without Gandalf, Aragorn leads the Company to the golden wood where dwell two high elves who distrusted Sauron already in the Second Age. I agree with Eamila Bolger that in Lórien Tolkien takes the opportunity to redraw the enchantment he had first created at the house of Tom Bombadil. Only now the magic voice of Bombadil (that all obey without question) is transmuted into a profound engagement with elvish vision and communication between elf and mortal. This communication is spelled out fully only in the cases of Frodo and Sam (and perhaps Boromir too, later, by implication), and only Frodo fully sees the Lady, although she sees all of them - 'sees' directly, of the mind, without intermediary of words or other medium, and Frodo Baggins then offers her the Ring and sees the Lady. In my opinion the scene in the Mirror is the highlight of the book, and this despite the fact that it is a deliberately non-dramatic moment: here stands Galadriel and Middle-earth, on the brink, at the moment of temptation and possible Fall - but both she and Frodo make the right choice, shoulder the consequences of their choice, and continue with what they must do: the drama is averted, leaving them only the consolations of northern art.
5. Falls of Rauros
Now we have drama! The Fall of Boromir. And also Frodo's mega-weird TV spectacle experience on Amon Hen.
-- And only now do we enter the The Two Towers; but I say again that this part of the story really begins at Moria, or with the second book of Fellowship. Yet there is a change as we step into book III, and now it seems to take Tolkien a while to get into his new stride - lots of chasing of hobbits into and over the great plains of Rohan, and the hobbits themselves running and getting lumped and bumped about - till we reach the first sign of Rohan - Éomer and his riders, and suddenly it is all happening around our ears.
The first meeting with Éomer sets the scene for the story in Rohan - all this talk of war and trust in the words of a stranger and legends springing up out of the green grass. And then suddenly we have this night-time hallucination of Gandalf who is perhaps only a sending of Saruman (cf. the ambiguous figure in white seen by Frodo in the Mirror) while Peregrin Took and Meriadoc Brandybuck have taken up with a walking, talking tree!
After the Falls of Rauros we enter a different Middle-earth, more properly, the South of Middle-earth; where the vegetation is different and the old towers that are but ruins in the North still house great lords and magicians and some forgotten, ancient, elvish, seeing-stones. It is indeed the world that Boromir has talked about at the Council of Elrond, ultimately here is the surviving remnant of Numenor of old, but it is interesting that Tolkien chooses to lead us to Gondor only by way of Rohan, Saruman, and the Ents.
My basic sense of this part of the story - Rohan, Fangorn, Isengard - is that, having worked through the 'high magic' at the heart of the story in Lorien Tolkien is now easing it down and showing us how this same 'magic' appears to - and is even employed by - mortals, like us.
For what it is worth, I think that the story of Saruman is prefigured on the gates of Moria. Saruman and Wormtongue are surely lesser versions of the 'unfriend' who poses as a 'friend' pointed to on the Doors of Durin; Third Age versions of Sauron the Necromancer of the Second Age.
And then we have the Riders of Rohan! Beloved by all good hobbits; because the Rohirrim are but hobbits at a more primitive and martial age of their history; Meriadoc travels in time as well as space, hearing a language spoken around him that he seemed to recognize but, though spoken more slowly and sonorously than the tongue of the Shire, he cannot fathom the meaning of. It is just as when I listen to Old English. The barrow mounds on the road to the gate of Edoras, the appointed ends of Eomer and Theoden - the first, king who will be, who accepts Aragorn as a fairy-story come to life on their first meeting, and the second the king who has listened to craven counsel but now hearkens to the name of the Lady and the hope of the wizard, and who rides out to war and, though not yet, his death.
And then, finally, we have a Palantir and the hobbit Pippin is questioned silently by Sauron the Ensnarer. The face and the mental-speech of Sauron has been framed in a dark globe of crystal.