My attempted completion of Frodo's poem: O! Wanderers in the shadowed land

Frodo, Sam, Merry and Pippin are in the Old Forest...

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Frodo tried to sing a song to encourage them, but his voice sank to a murmur. 

O! Wanderers in the shadowed land
despair not! For though dark they stand,
all woods there be must end at last,
and see the open sun go past:
the setting sun, the rising sun,
the day’s end, or the day begun.
For east or west all woods must fail…

Fail - even as he said the word his voice faded into silence. The air seemed heavy and the making of words wearisome. Just behind them a large branch fell from an old overhanging tree with a crash into the path. The trees seemed to close in before them.

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It's a lovely lyric; but - thanks to the increasing threat of the Old Forest, it never gets completed. The commentary in Christopher Tolkien's The History of Middle Earth seems to suggest that the poem was never taken any further. 

So, I thought I would have a shot at providing a final line for the poem - by completing a rhyming couplet beginning with For east or west all woods must fail… 

I can immediately inform you that I failed to attain an altogether satisfactory result; the the best completion I managed, the one that is most in spirit with the rest of the poem is:

For east or west all woods must fail…

East or west, all woods must fail.

But that is very obviously pinched from Robert Frost's poem that ends with a repeated "And miles to go before I sleep"...

The ideal last line would either complete the argument, or else explain why the poem stopped. 

So, here are a few other suggestions, from which you can take your pick - or yourself try to do better. 

For east or west all woods must fail…

If not at Harvard, then at Yale. 

For east or west all woods must fail…

It's like escaping from a jail!

For east or west all woods must fail…

And that's the ending of my tale.

Perhaps the best, however, is surely:

For east or west all woods must fail…

Alas! I've trodden on a nail.

 

POSTCRIPT:

Following a to and fro at my BC's Notions blog, and using the breakthrough provided by WmJas Tychoneivich, this is my personal preferred version of the completed poem:

O! Wanderers in the shadowed land
Despair not! For though dark they stand,
All woods there be must end at last,
And see the open sun go past:
The setting sun, the rising sun,
The day’s end, or the day begun.
For east or west all woods must fail
As out of shadow wends our trail.