Imagine a forest.
The soil is black and deep. The sun is yellow and high in the brilliant azure sky. You can't see the soil though, or the sun, because the ground is covered in roots and moss and ferns and discarded leaves. And the canopy of the forest, that's thick and green. It's full of flowers, lianas, and thin branch ends quivering in the breeze.
You can smell the hidden soil. Thick and black and moist and earthy and good. You can feel the warmth of the sun and admire the way its light dapples downward. This isn't a dark forest. This is a bright, living, growing, silent place.
There are no men here. No animals. No insects or birds.
Imagine a rhetorical question.
Or a philosophical one. It depends on the person asking. It's an old question about a quiet forest full of trees, and what happens if one of those trees falls. Creak-Whoosh-Crash! Who hears it?
You know the answer of course. You imagined the forest, you must know. It's very obvious. No men. No animals. No insects or birds.
After the Battle of Canary Wharf, the Doctor tries to delete Rose's room. The TARDIS won't let him. He thinks that the ship is being sentimental so he yells and crashes around the console room and generally makes a fool out of himself. Not caring. Until a small blinking light alerts him that the safety over-rides have kicked in.
The TARDIS is, theoretically, when operating correctly, meant to protect the lives of all those who travel aboard her. Even if doing so means disobeying Doctor's orders.
"There's nothing in her room. She's not there," he shouts.
The console room is green, organic. Like an underwater forest. A growing, knowing place. Full of silence.
The Doctor hits the central console with his fist. Which hurts. "She isn't here. She's gone."
Eventually, he forces himself to her room. He stands in the doorway of it and tries to be dispassionate. Steel and fire and ice. He almost succeeds.
The room is messy and full of pink and frilly things (which clash with the green metal and coral struts). There is a small potted plant on the night table. The Doctor picks it up. He feels the heft of the light-looking clay pot. He smells the richness of the soil and the slightly spicy tang of the leaves. A present from a tree at the end of the world.
"In peace and good faith," he murmurs, picking it up.
That was their first date, him and Rose. The end of the world, because he was a broody, angst-ridden Time Lord who thought, "Hey, let's have something in common shall we? My world got blown up. Well, no, actually I blew it up, but never mind that. We both know what it's like to watch our homes burn away to dust. How romantic."
And he'd met Jabe there. Jabe who he'd forgotten, up until now, even though he'd got her killed. She'd said that her purpose on Platform One was to show respect to the Earth, and to mingle, and to be seen.
Those reasons might have been true, but the Doctor knew that Jabe and her brothers had also come to the party to spread clippings of their grandfather. An old business trick and not entirely ethical. She wanted the guests to take home the clippings, plant them, and then in fifty, one hundred, one thousand years (trees are nothing if not patient), after the clipping had spread and colonized. Then the Forest of Cheem would swoop in with lawyers to determine squatter's rights, citizenship details, and — if they were being really nasty — genetic material infringement retribution.
He holds the pot in one hand and thinks about screaming and throwing it at the wall and watching the clay shatter and the earth scatter across the grated floor. Instead, he cradles it against his shirt and hunches out of the room.
"Are you satisfied?" he asks the ceiling after crossing the threshold.
There is a hum, and the room disappears behind him.
Rose is gone because of him. Jabe died because of him. So many live torn apart because of him.
To Rose it was just a potted plant. To him it's just a pot full of nuisance and bad memories. He gives it to Sarah-Jane. She has a garden.
Sarah-Jane has Jo Jones, née Grant over for tea.
It doesn't happen often. They're both far too busy: aliens to help, articles to write, protests to attend, shady corporations to investigate, children to look after, football practices, skyping with Luke and Clyde and Rani, helping errant husbands in the greenhouse…
It makes the occasions when they do get together even more special.
"That's a new plant," Jo says, putting down her mug (which is filled with something far stronger than "tea") and walking over to its stand by the window. "Look at its little leaves! It's darling. Cliff would love this. Do you know what species it is?"
Sarah-Jane shrugs expansively. "Your guess is as good as mine. I found it on the doorstep."
"He leaves you presents?" Jo asks, pulling a mock-scandalized face.
Sarah-Jane takes a sip of "tea" and smiles. "I assume that it will grow to be eight feet tall, drip venom, and attempt to eat me. After setting the house on fire."
"Cliff really would love it," Jo says.
"He can have it then, if you'd like. I'm surprised it hasn't died already. I'm terrible about watering house plants."
"It will have a good home," Jo says, playing with the plant's leaves. " And I promise to make Cliff promise to always keep a fire extinguisher nearby. Just in case."
Can you still imagine that forest? Do you have an answer for the question yet?
A tree falls —
But where is the forest it falls in? When is the forest? Why is there a forest?
Well, that's a long story. There's this young tree named Jabe who is named heir to the Cheem fortune (the trees of the forest have roots everywhere, and there is always money in land). Her first duty is to mingle with the rich and powerful — and to gift them with clippings of her grandfather. Little Trojan houseplants to help the Cheem forests grow and prosper.
Except things didn't go as planned. Jabe died and most of the clippings were left forgotten on Platform One when the guests evacuated. The Platform was decommissioned. A cold metal box. The clippings withered and died — all except one.
The only clipping to survive wasn't taken home by a celebrity, or a politician, or a CEO. It went into the hands of Rose Tyler, ordinary nineteen year off of the Powell Estate.
It got passed from her to Sarah-Jane Smith: mother, journalist, occasional action hero.
It got passed again to Jo and Cliff Jones: happily married hippies, doting grandparents, activists, and world travellers.
It went into a greenhouse full of clippings and pots. Plants from around the world. Plants from out of this world. Lots of mushrooms. It sat there for a very long time.
Jabe's grandfather took the opportunity to pollinate with the strange and exotic fauna surrounding him. A few dozen millennia later (trees are patient) his children covered our world and several others.
A tree falls in the forest. Creak-Whoosh-Crash! A seed is planted in the gap. Little Jabe grows up (literally), a proper young sapling who knows not to show her lianas in public. A future heiress who has a sap-deep instinct that she will one day be responsible for something greater than herself. Greater even than the Cheem corporation she represents.
But it wasn't until she met the Doctor that she understood. Her metal machine didn't want to name him. It was confused by his existence. The universe had forgotten, but she didn't. How could she? Her people always recognize him, whatever his face.
Wherever he goes, the Doctor cannot hide from the trees.
It's not because of his role in their genesis, and It's not because of his exploits saving worlds and galaxies.
It's because of the amazing, bigger-on-the-inside, blue box that he travels in. The spaceship made of wood.
When a tree falls, all the others hear.
And that blue box is always falling on its way to somewhere else.