I wrote Bitter Harvest AFTER a Ten story called Dead Tired, in which people in fourteenth century Cumbria were dying of starvation after falling into unexplained comas. There is THIS paragraph in the story.

“What did they die of?”

“Starvation,” The Doctor answered. And he looked around. He’d seen people die in famines. He’d seen it in 20th century Africa and nineteenth century Ireland, as well as a particularly harrowing time on a planet called Vorlox II where the people had starved amidst abundant harvests because of a strange virus that meant none of their food, no matter how much they ate, gave them any nutrition at all. That was one of a thousand haunting memories that sometimes gave even him the creeping horrors in the quiet of the night.

I knew then, that I would have to tell the story of Vorlox II as a Theta Sigma story. Inbetween that harrowing story of the people dying amidst abundant harvests, I put the story of Natalie’s relationship with the Eye of Harmony, which had been mentioned in passing before, but needed to be made more explicit. There is going to be a payoff with this, but not yet.

Chrístõ coming up with the cure in the nick of time IS very Deus ex Machina. Yes, that is freely admitted. But, so what? It’s fiction. And after all, Chrístõ IS a smart man. Why WOULDN’T he get it?

The scene in the in potentia room, served to lift the spirits a little after the sadness and despair of the planet, and allowed me to get in something I wanted to use, but which I couldn’t make a WHOLE story out of – W. B. Yeats’s Nine and Fifty Swans. I really wanted to put either Chrístõ or The Doctor into that scenario, but there just WASN’T a story in it. So it became a gentle little vignette at the end of this story.

The Wild Swans at Coole

THE TREES are in their autumn beauty,
The woodland paths are dry,
Under the October twilight the water
Mirrors a still sky;
Upon the brimming water among the stones
Are nine and fifty swans.

The nineteenth Autumn has come upon me
Since I first made my count;
I saw, before I had well finished,
All suddenly mount
And scatter wheeling in great broken rings
Upon their clamorous wings.

I have looked upon those brilliant creatures,
And now my heart is sore.
All’s changed since I, hearing at twilight,
The first time on this shore,
The bell-beat of their wings above my head,
Trod with a lighter tread.

Unwearied still, lover by lover,
They paddle in the cold,
Companionable streams or climb the air;
Their hearts have not grown old;
Passion or conquest, wander where they will,
Attend upon them still.

But now they drift on the still water
Mysterious, beautiful;
Among what rushes will they build,
By what lake’s edge or pool
Delight men’s eyes, when I awake some day
To find they have flown away?

http://www.bartleby.com/148/1.html