The singing drew nearer. One clear voice rose now above the others. It was singing in the fair elven-tongue, of which Frodo knew only a little, and the others knew nothing. Yet the sound blending with the melody seemed to shape itself in their thought into words which they only partly understood. This was the song as Frodo heard it....
If the power of Elvish song is such that those who do not know Elvish still understand it, as Frodo, Sam, and Pippin do when they encounter Gildor's troop in the woods of the Shire, why don't they also understand the lament of the Elves of Lothlórien for Gandalf, which Legolas refused to translate because it was too difficult and too painful (FR 2.vii.359); and why does Legolas feel the need to translate the song of Nimrodel (FR 2.vi.339)?
Or is it only poetry in Quenya and Sindarin that have this power? Legolas makes clear that the poem about Nimrodel is 'in the woodland tongue', by which he means the Silvan Elvish descended from Nandorin. Since the Elves of Lothlórien were of the same folk, their lament for Gandalf, which Legolas alone of the Company understood, was also in Silvan, or so it would seem. For, had it been in Sindarin, Aragorn and Boromir at least would have understood it.
This raises the intriguing and likely unanswerable question of why only song in Quenya and Sindarin might be capable of this effect. At first I thought that the power might be proper only to the High Elves, or Calaquendi, like Gildor or the minstrels in Rivendell, who are Noldorin. It would make a certain sense if singers who had dwelt in Valinor and seen the Light of the Trees possessed this ability, except that song the hobbits hear in the Shire is in Sindarin, and Daeron of Doriath, is said to have been 'the greatest of all the minstrels of the Elves east of the Sea, named even before Maglor son of Fëanor' (S. 183). It is perhaps not irrelevant here that Doriath had a twofold connection with Valinor, namely Thingol and Melian; and in the time of Daeron and Maglor, the fading of the Elves had scarcely begun. Still what we seem to be seeing is a clear distinction in powers of enchantment between different kinds of Elves.
We also should not ignore the two songs Galadriel sings before the departure of the company from Lothlórien. The first, 'I sang of leaves' (FR 2.viii.372-73), they apparently understand at once, just as they did the hymn to Elbereth in the Shire and the songs at Rivendell. The narrator makes no comment to draw the reader's attention to their understanding of the language. Nor does he have any need to do so because of the continuity with these passages. On the contrary, it is precisely the failure to understand the songs of the woodland Elves that the narrator considers worthy of note.
In the case of 'Namarië', however, we find something strange and rather different, something which has had me wondering for decades and which I now believe I understand at last. After Galadriel sings in Quenya, the narrator calls out the fact that Frodo has not understood her song, though he remembers the words and translates them, with difficulty, 'long afterwards'. Suddenly, the song of this most powerful and majestic of all the Elves in The Lord of the Rings, a lament to Varda herself in the language of Elven song, fails to convey its meaning to its audience, just as the songs of the woodland Elves did.
The translation, moreover, is also into prose, not verse, which is odd in itself, given the power of Elven song to come to life, as it were, in the minds of its audience (FR 2.i.233; S. 140-41, 171). Finally -- and perhaps this is just a matter of taste -- that prose rendering, while sturdy and serviceable, has always seemed rather bookish and not the masterful elegy Galadriel's lament calls for. The rather intrusive 'scholarly' gloss on 'Varda', which we are probably meant to regard as the work of a later hand, only reinforces the lack of enchantment we find here. The answer, I would argue, lies in the introduction to the poem:
On the green bank near to the very point of the Tongue the Lady Galadriel stood alone and silent. As they passed her they turned and their eyes watched her slowly floating away from them. For so it seemed to them: Lórien was slipping backward, like a bright ship masted with enchanted trees, sailing on to forgotten shores, while they sat helpless upon the margin of the grey and leafless world.
Even as they gazed, the Silverlode passed out into the currents of the Great River, and their boats turned and began to speed southwards. Soon the white form of the Lady was small and distant. She shone like a window of glass upon a far hill in the westering sun, or as a remote lake seen from a mountain: a crystal fallen in the lap of the land. Then it seemed to Frodo that she lifted her arms in a final farewell, and far but piercing-clear on the following wind came the sound of her voice singing. But now she sang in the ancient tongue of the Elves beyond the Sea, and he did not understand the words: fair was the music, but it did not comfort him.
Yet as is the way of Elvish words, they remained graven in his memory, and long afterwards he interpreted them, as well as he could: the language was that of Elven-song and spoke of things little known on Middle-earth.(FR 2.viii.377)
Lothlórien, as Verlyn Flieger has argued (1997: 89-115, 192-97), is the supreme example of Faërian Drama, where, to use Tolkien's words 'you are in a dream that some other mind is weaving, and the knowledge of that alarming fact may slip from your grasp' (OFS ¶ 74). Galadriel has already told us that Spring and Summer will never again come to Lothlórien (FR 2.viii.375). This song is over. Frodo does not understand 'Namarië' because the spell is broken. The curtain has come down on Faërian Drama, and Frodo must parse out his Quenya like the rest of us, huddled beneath our midnight lamps.
'Yet if you succeed, then our power is diminished, and Lothlórien will fade, and the tides of Time will sweep it away. We must depart into the West, or dwindle to a rustic folk of dell and cave, slowly to forget and to be forgotten.'
Then she let her hand fall, and the light faded, and suddenly she laughed again, and lo! she was shrunken: a slender elf-woman, clad in simple white, whose gentle voice was soft and sad.
'I pass the test,' she said. 'I will diminish, and go into the West and remain Galadriel.'