Once upon a time, in the days of Megan the Destroyer, when the world was new and ponies first came to Equestria after the death of Queen Majesty, there was a wizened little creature called the Moochick who was the only being willing to teach magic to the young race of ponies.
“Teach us!” they cried, and sat patiently while he shifted his old bones into a more comfortable position on his mushroom chair.
“I will only teach magic to the race of ponies who is able to build me a house,” he responded.
The three races of ponies raced away to complete the task, each of them eager to prove they were the ponies who deserved magic. The earth ponies built him a strong house of bricks, tall with many windows and doors. The unicorns constructed a house of crystal, with tall towers and parapets. And the pegasi built a huge cloud mansion with flowing fountains and colorful rainbows.
Returning to him, they watched as he examined their work.
“Bricks?” he asked, looking in the earth pony house. “They are rough and will scratch my sensitive books until there is nothing left but tatters. No, this simply will not do.”
“Ouch!” he declared when looking into the unicorn house of crystals. “How sharp these walls are, and the light pours through at all times of the day. My precious books will all be ruined and faded. No, this also will not do.”
The cloud house he simply looked up at, standing on the ground with his hands on his hips.
“No, my little ponies,” he said. “None of these houses will do. But do not despair. I shall give you one more chance to prove your worth.”
The three races of ponies trudged away, dejected and disappointed, until a young earth pony said, “He told us all the things he does not like in a house, but what does he like?”
They all sat and thought for a while.
“He likes plants and trees,” said an earth pony. “Perhaps we could make him a tree house.”
“He does not like to be high in the air,” said a pegasus. “Could the house be inside a tree?”
“That would be too small,” said a unicorn. “He loves his books. A house inside a tree would be too small unless we could make it grow.”
“I’m good at making apple trees grow,” said the earth pony, “but they’re not very big. We would need something bigger, like an oak.”
“I know where the largest oak tree in the forest is,” said the unicorn. “I shall bring back an acorn, and if you can make it grow, it will make a fine house.”
“I can bring water and give the tree plenty of sunshine,” said the pegasus.
And the three races of ponies each eagerly went to their task. The unicorn brought back the largest acorn that anypony had ever seen, the earth pony buried it in the richest soil she could find, and the pegasus brought cloud after cloud of water to make it grow. Sooner than they expected, a large oak tree graced their tiny village, and the Moochick looked it over with a nod of his head.
“Perfect!” he exclaimed. “I shall move in at once.”
“But what of our magic?” asked the ponies.
The Moochick laughed. “Silly ponies. You have had your magic all along. The earth ponies had the magic of making things grow, the pegasi have the magic of the sky that they use to bring forth the rain and the sunshine, and the unicorns possess the magic of knowledge.”
Both the pegasus and the earth pony nodded their heads, as the Moochick was wise indeed, but the unicorn was still troubled.
“There are many things in the world for us to learn, but so few unicorns. How can we best learn what we do not know and pass our knowledge on to others?”
The Moochick laughed again. “You are the silliest of all ponies. The answer is in what you have built, for this tree shall contain books in which you will write that which needs to be passed down to others, and in which you will find the knowledge which you seek.”
And all of the ponies nodded their heads at the wisdom of the wise old creature, and declared that there would be a gathering place for knowledge in each of the cities that they built as their numbers grew. The pegasi and unicorns built huge libraries in Canterlot and Cloudsdale, but the earth ponies took the acorns from that first hollow oak and planted them across Equestria in every small town and village, so that the knowledge that they contained could always be nearby, and that the gift of the Moochick would never be forgotten.