Upgoer 5 is a description of a Saturn 5 rocket created by xkcd.com artist Randall Munroe.
See here: http://xkcd.com/1133/

For this, he uses a vocabulary that consists of no more than ‘ten hundred’ words. The following description uses no more than that vocabulary.

Living things make more of themselves. It is one of the special things about living things that they make more of themselves. Some things make more of themselves all on their own. They are usually very simple things which are too small to see with your eyes. If you could see them, they would look like tiny bags which you can see through. These things make more of themselves by themselves. Some of them just cut themselves into two, in a special way, so that the two parts are both exactly like the first thing. Because they are exactly like the first thing, these things don’t change over time. All of the new ones are just like the first ones. It doesn’t matter how long you wait, all of the later ones would be the same as the first one.

If something happened in the world which meant that these things couldn’t live any more, they would all die because they are all the same. But there are still a lot of them around even though they got started maybe ten hundred hundred hundred hundred years ago, so it can’t be that bad a system.

Other things don’t do this. Lots of animals make more of themselves by getting together with another animals of the same sort. These animals aren’t exactly the same as each other even if they are of the same sort. They have tiny ways that they are different from each other. They make another one of themselves by each giving a bag of stuff which turns into the new one. Half of each bag of stuff from each of them gets put together and it all turns into a new one which is different from both of them. You can see this where a man marries a woman and they have a baby which is different. For a start, the baby will either be a man baby or a woman baby (some people think this is a wrong thing to say, but we can’t worry about that now). But the woman might have red hair, and the man might have dark hair, but the baby will either have dark hair or red hair. The woman might be tall and the man short, but the baby will grow up short or tall.

When lots of animals do this, it means that there are lots and lots of different ones in all of the animals of the same sort. Because animals have lots and lots of babies, usually, they don’t always live long enough to be able to have any babies themselves. Most babies get killed in some way before they get round to having their own babies. Often they are food for other animals. Sometimes they are born with something wrong with them. ‘Something wrong’ can just mean that they can’t live in the world the way it is where they live. A baby fish which can’t breathe in water will die almost at once. But a baby fish which is faster at moving in water than all its brothers and sisters might be able to stop itself getting killed by the animals that want to eat it, by going faster in the water. Those babies will more often make more babies because they won’t get eaten as often. And some of their babies will also be faster fish, maybe even faster than them. So there will be more of the faster fish. If the only fish left are the faster fish, then the baby-eaters will have to go faster to catch them or they will die from no food. So only the faster baby eaters will live.

In this way, over a long time, the fish will change, getting faster and faster. Another way not to be eaten by the baby eaters will be if the fish are hard to see. So maybe instead of the slower ones getting eaten, it will be the bright colored ones that get eaten, leaving only the dark colored or see through fish to get away. After a long time, the fast fish might be completely different from the dark or see through fish. They have each found a different way to avoid getting eaten. If they are very different, then if one of the fast fish and one of the other sort got together, they might not be able to make other babies. This is when we know they are really different sorts of animals.

Lots of people think this means that animals are always getting better, for some reason, and they even think that people are the best, because they are quite a new kind of animal. This is not right. Animals which live in people’s insides are no less ‘got better’ than people, because they are just as good at living as the people. They also think that this cannot be right because there are tree-bears and there are people. ‘Look, how can people have come from tree bears’ they say, ‘if there are still tree bears?’ Such people have not understood that in fact, tree bears and people had the same long back man parents and woman parents. Maybe they looked a lot like a tree bear, but they were different. Now some of their children turned into tree bears, and others turned, very slowly, into people.

It is very hard to believe that people came from tree-bear-go-before animals, because people like to believe that they are special, and that they are not just animals like tree-bears and dogs and cats. They have also been told that God made all people, by picking up some dirt and breathing on it. They like to think that they are made by God breath, and not because hundreds of hundreds of hundreds of other animals have died instead of them. If they are God breath, they think, God will take them to a special nice place when they die. Just liking the idea that something is true, though, doesn’t make it true. They often don’t realize this.