It is five o’clock on a December evening, but I have not yet closed the curtains. On my desk, in front of me, warm in the lamplight, are the loose pages of the paper I have promised to review. A sensible piece of work, and good science. Well written too. The writer, a very promising young man, knows a great deal about measuring chromium impurities in crystalline aluminium oxide.

In short, he knows why rubies are red.

I no longer teach, no longer even give lectures, but I am not entirely forgotten. Old students visit me and tell me of their work, sometimes send me papers. To avoid disappointing them, I’m forced to keep myself up to date with the latest knowledge, the latest thinking. I am not ready yet to be thought a helpless old lady.

But tonight, looking out over the park, I have no appetite for my subject. I too have some knowledge of the chemical composition of gemstones, but when someone talks to me of rubies it is not a scientific formula that leaps into my mind.

Outside, the first snowflakes of winter are beginning to fall and tonight they remind me of a different evening, a lifetime ago, when the winters lasted forever and the streets below me rang to the clip of horses’ hooves…