Once upon a time there were two shapes: a Circle and a Square. They stumbled across a piece of fruit one day, and inside that fruit there were six seeds. Being fair and equal and perfectly nice to each other, each of them took three seeds back to their home.
All three of the Circle's seeds sprouted and made wonderful trees, but the Square only got two trees. "Ah, that's just the luck of the draw," said the Circle. The Square agreed.
The two shapes continued to grow their trees until the trees eventually bore fruit. On the very day that the fruit trees' fruit became ripe, a visitor from out of town came and decided to buy all of the fruit that both of them had. Circle had three trees, and Square only had two, so Circle ended up making 50% more money than Square. "Ah, that's just the luck of the draw," said Circle, and Square agreed.
After taking care of their basic expenses, which were exactly the same as each other, Circle had quite a lot more money left over than Square, and was able to use that money to buy more trees with which Circle could make more money. Square, however, did not have as much disposable income, and had to be a lot more careful with the profits in case something bad happened to wipe all of the savings out.
Over time, this continued more and more; Circle had more profits and was able to direct more of them into new trees, while Square was stuck with only the two trees. Circle could also afford to hire more people to manage everything and branch out into multiple franchises, which led to an even more rapid accumulation of wealth, whereas Square was still only scraping by.
One day, another visitor came from a far-away land, and decided to bestow a great reward onto whomever was the best fruit farmer in all the world. Well, this was clearly Circle, as Circle had an entire orchard of fruit-bearing trees and an entire fiefdom of workers, while Square only had two trees and a staggering level of debt. The visitor decided that because Circle was such a great farmer, that all of Circle's living expenses should be reduced further, to make it easier for Circle to keep on creating jobs and expanding the economy.
At this point, Square was getting a little bit frustrated. "Circle, you have done an excellent job at growing your fruit empire, but what about me? I work just as hard as you and yet I only scrape by on the two trees I had to start with. Because we were sharing in the original seeds equally, it seems only fair that I get a percentage of the other fruits that you got simply because you had an extra tree."
"COMMUNIST! THIEF!" shouted Circle. And Square was thus thrown into jail, and with nobody to take care of Square's trees, they withered and died.
Circle and Square each had an equal number of children, and each of those children wandered the world to find new fortunes in other places.
Upon seeing Circle's children, the people in the far-off lands said, "Oh, you are a Circle! I have heard many great things about your lineage. Here, you may help to take care of our farm, as we know that Circles are excellent at farming."
Upon seeing Square's children, the people said, "Oh, you are a Square. I have heard about you - your kind are lazy, and cannot even keep two trees alive. I suppose you can have a menial position working for the manager - that Circle standing over there - but we will be watching you closely."
The young Circles all made their fair share of mistakes, but because Circles are excellent farmers, these mistakes were overlooked. But sometimes these mistakes involved a Square, and in those cases, this would result in instant punishment for the Squares, because it only served to prove that Squares could not be trusted.
Eventually, new shapes came around, but everyone assumed that because of their sharp corners they were just as unreliable and criminal as the Squares. Some of the many-sided shapes like Octagons and Dodecagons looked enough like Circles that they were given a bit more leeway - "Oh, if you were to just file off your corners you'd be just as good as a Circle" - but none of them managed to ever escape from the economic divide.
One day a Triangle found a fruit by the side of the road, and kept the seeds to start a fruit tree. Everyone assumed that the fruit had been stolen from a Circle's farm and, while nobody could prove it, nobody bought the Triangle's fruit, because even if it wasn't stolen, there was probably something wrong with it. After all, you can't trust a Triangle.