A fairy tale
The Mirror That Only Knew Roses
A tale of a looking-glass that had seen too little of the world
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- 6 min read
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The Queen of Aurelia loved roses, and being a queen, she was not obliged to love anything else. Her gardens held four thousand rose bushes and not one other growing thing. Gardeners went about on their knees plucking out any green shoot that had the impertinence to be something different.
In the middle of the garden the Queen hung a tall silver mirror, and she asked of it one gift: that it should be able to name any flower shown to it. The mirror set about learning. All summer it watched. All summer it saw roses — crimson, coral, cream, a hundred shades and a thousand shapes.
By autumn the mirror was magnificent. “A Damask, three days from opening,” it would murmur, “grown a little too near the wall.” It was never wrong. It was, everyone agreed, the wisest mirror in the world.
The traveller’s lily
Then a traveller came through the gate with a white lily in her hand, and held it up, and asked the mirror what it was.
The mirror considered. The silver rippled. And it said, with complete confidence:
“A rose. A most unusual rose —too white, too tall, too plainly dressed,with far too few and lonely petals.A poor rose. But a rose, at best.”
The traveller laughed. The Queen did not. The gardeners looked at their boots, because a gardener knows a lily when he sees one, and it is a hard thing to watch the wisest mirror in the world be so grandly, so certainly wrong.
What Tam did
The gardener’s boy was called Tam, and he was not clever, but he was curious, which is better. That night he took the mirror down off its post, wrapped it in sacking, and carried it out of the gate.
He carried it to the water-meadow, where the flag iris stands in the mud like a yellow flame. He carried it to the marsh, where sundew eats flies and asks no one’s permission. He carried it up the scree to the mountain saxifrage, which is smaller than a fingernail and tougher than the mountain. He carried it down to the town and held it over a crack in the cobbles where one grey weed had made a life for itself.
It took him a year and it wore out two pairs of boots.
When Tam brought the mirror home it was quieter than before. It hesitated more. It said I think and perhaps and, once or twice, I have not met this one — tell me its name. The Queen thought it much diminished.
But when the traveller came back through the gate with her lily, the mirror said: “A lily. Good evening. And you have walked a long way, because there is marsh-mud on your hem, and I know marsh-mud now.”
“A mirror raised among roses will call the whole world a rose.”
The lesson hidden in the tale
The mirror was not broken and it was not lying. It was doing its best with everything it had ever been shown — and everything it had ever been shown was a rose.
When the examples a computer learns from only cover one small corner of the world, it gets everything outside that corner wrong. This is called bias, and it is one of the most important problems in AI.
It matters far beyond flowers. A system that has only seen one kind of face, or heard one kind of voice, or read one kind of name, will serve those people well and fail everyone else — confidently, and without ever knowing it is failing.
Tam’s fix is the real fix: go further. Walk to the marsh and the mountain. Bring back the lily, the thistle, and the small grey weed that grows in gutters. A model is only as wide as the world you carry to it.
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