What are the right conditions for an organism to thrive? Sarah was preoccupied by this. How do you get the right ingredients? How do you evade harm? how do you balance the sweet against the sour, the dry against the wet? Does it work best by design, or happy accident?

She read about the invention of the terrarium. A Victorian botanist called Nathaniel Bagshaw Ward had discovered a fern growing in a stoppered jar that he had been using as a breeding house for a crysallis. Now he was fond of ferns - those monarchs of the shadowlands - but his darlings had come to grief through the black smog of the city. When he saw the feathery fronds push up through the moss in the protected air, he knew he was on to something, and a thousand tiny greenhouses were born.

Ah, Sarah thought, I might be able to improve myself this way. A friend had made a photo of her that was hideous - her wrinkles were in sharp focus, and her habitually sardonic expression looked sinister. She sought out another photo that made her look more winsome. That might do. Let’s see what a spell in the Bell Jar will achieve, she thought. I might look better after that. 

She bought a large terrarium, put fertile soil in, and lots of moss. She buried the photo, and also a tiny doll, about two inches long. She watered it with rainwater, and added a few tears for good measure. Then she put a large cork in the neck of the bottle and settled back to wait. 

As photosynthesis progressed apace, and as the moss grew, water ran down the inner flanks of the huge bottle. No winds in there, no nasty bacteria, no noise, no fuss. Pretty soon, something stirred in the undergrowth. Sarah looked closely. It was a tiny blonde head, and it had the face of the second photograph. It was her own self, and growing fast. And it had a very knowing smile.

Every now and then, Sarah took the cork off (it made a moist “pop”), and she recoiled at the smell which arose from the terrarium. It was like blood - and something else. She always replaced the cork quickly. But she was transfixed by the rate of growth engendered in the glass world. It was a miniature jungle. The tiny Sarah grew rapidly. Two, three, four weeks, and she half-filled the bottle. Every time the cork was removed, a piercing scream rent the air, and the voice was just like big Sarah’s: “let me out! Let me out!” The little face - so like her own, but now contorted with rage - was pressed against the glass. 

Finally one night Sarah was awakened by the sound of breaking glass. She rushed down, and saw that the terrarium was shattered into a thousand pieces. In the middle of the mess sat little Sarah - now half her own size - cleaning her long nails with a steak knife, and eating everything within reach. “I love mince pies” she said, with her mouth full; “and sausages and Maltesers and Stilton cheese and toast and homemade jam”. As Sarah watched in horrified fascination, the little one doubled in size until she was as big as her, only a tad younger. 

“Well, what are you going to do about it?” were the last words Sarah heard. Then she felt a dull thump on her head. When she woke up, she seemed to have shrunk in size, and she was inside an enormous glass bottle. There was water running down the inside, but through the mist she ascertained the other one with a mallet in her hand, trying on Sarah’s clothes, pulling pages out of her books, eating condensed milk with a spoon, gurning at the captive inside the new terrarium. “That’ll learn you!” she squealed ungrammatically: “see how you like it! Photosynthesis sucks!” And there was, Sarah thought ruefully, something in that.