What's really amazing is how much of the language remained relatively unchanged, even when the significance of what was being said changed mightily.
A lot of the fun, really, of reading the drafts of Book I and on into II as far as Moria is how Tolkien kept prose, even dialogue, largely intact whilst the dramatis personae
rotated beneath it, so to speak. But perhaps the most striking example of keeping language relatively unchanged when "the significance of what was being said changed mightily" is found back in Chapter 3 (the second one written:)
They ran quickly to the left down into a little hollow beside the road and lay flat. Bingo slipped on his ring and sat down a few yards from the track. The sound of hoofs drew nearer. Round a turn came a white horse, and on it sat a bundle -- or that is what it looked like: a small man wrapped entirely in a great cloak and hood so that only his eyes peered out, and his boots in the stirrups below.
The horse stopped when it came level with Bingo. The figure uncovered its nose and sniffed; and then sat silent as if listening. Suddenly a laugh came from inside the hood.
'Bingo my boy!' said Gandalf, throwing aside his wrappings.....
Then Tolkien went back with a pencil and corrected a few words on the manuscript:
Round a turn came a white [> black] horse, and on it sat a bundle -- or that is what it looked like: a small [> short] man wrapped entirely in a great [added: black] cloak and hood so that only his eyes peered out [>so that his face was entirely shadowed], and his boots in the stirrups below...