Once upon a time the god of breaking rules walked the earth in the form of a handsome alicorn stallion, for his love was a mortal mare.
His love was kind, beautiful, noble and heroic. In those days the unicorns and the pegasi did not exist, and only gods walked in the form of alicorns, so she was an earth pony, but she was a princess and had a noble heart. One day she died protecting Harmony and the kingdom. She was still very young, and all the ponies mourned their princess.
The god of breaking rules was heartbroken. And then, because he was the god of breaking rules, he decided he would break the rule of life and death and return his love to life.
This was the most sacred law of the gods. Thus, when he asked the council of the gods for leave to do this thing, as he was the god of breaking rules and therefore breaking this rule should be his right, they told him no. The law of life and death was a law that even the god of breaking rules could not be permitted to break, for it governed the natural order of things, and breaking it would bring chaos and disharmony to the world.
So the god of breaking rules thought and thought about how he could enact his plan anyway.
***
First he went to the sky. "Hello, sky, how are you on this fine day?"
"I am lonely," the sky sighed. "My only friends are the Sun and the Moon. Will you spend some time with me?"
"Of course!" the god said. "I'm lonely too. The mare that I loved is dead; only spending time with my friends can soothe my heart."
"You are my friend?" the sky asked.
"Of course we are friends. Just because you are the sky, and I break the rules, doesn't mean we can't be friends, right? Who wouldn't want to befriend somepony as beautiful as you?" He sighed. "My lost love was beautiful, but even her radiance couldn't compare to your loveliness, sky. Many times she would look up at you and rejoice in your beauty. I only wish..."
"What do you wish, god of breaking rules?"
"Your dresses are so beautiful and she would have looked so lovely in a dress like that. But now she is dead. I wish I had a scarf made from the fabric of your dress, that I could lay it on my love's tomb so she could wear it in the land of the dead, and remind herself of your beauty."
"That's so sweet," said the sky. "I think I have just the thing."
The sky drew forth two scarves, one from the fabric of her sundress, and one from the fabric of her nightgown. "You can have these, my friend. Lay them on the tomb of your love so she can remember me, in day and in night."
"Thank you, sky. Let me give you a gift in return."
The god of breaking rules lifted two ponies into the sky, a mare and a stallion. He blew on their backs and wings sprouted there, like the wings of birds. For in those days it was a rule, that only birds should have wings with feathers, and he was the god of breaking rules. "Here, sky. Here are two ponies with wings to be your friends. They will fly within you, and catch your clouds for you, and love you, and their children and their children's children as well."
"I love them!" sky said. "What a thoughtful present. I will call them pegasus!"
"You're welcome, sky," said the god. "It was no trouble at all."
Now the sky wanted to play with her new friends, so the god took his leave and went to visit the Sun.
***
"Oh, Sun," the god of breaking rules said. "You are so beautiful, it soothes my heart. For I have lost my mortal love, and the only thing that will ease my pain is if I can bask in your radiance."
"I am pleased to have you for a guest, o god of breaking rules," said the Sun. "I am very lonely too. I never have a chance to see my sister, for we can never spend time together in the sky. When I am awake she must sleep, and when I sleep she must awake."
"That's very sad," the god of breaking rules said. "And really quite unfortunate. Your sister has grown into quite a fantastic beauty! I believe you would be impressed."
Now the Sun was very vain. She loved her little sister, but it was important to her that everypony see her as the more beautiful of the sisters. So she said, "She isn't more beautiful than me, is she?"
"Who could think so! Although... well..." The god of breaking rules took a good long look at the Sun. "Now that you mention it..."
"She cannot be! How could anypony think my sister is more beautiful than me?"
"Oh, I'm sure nopony does," the god assured her. "She is very beautiful, but not quite as beautiful as you. It's just that she has so many lovely gems!"
"My sister has lovely gems?"
"Yes, all sorts of sparkling gems all about her. Of course she cannot match your radiance, but her gems do give her a subtle and startling beauty that... well, my dear, of course your unadorned beauty is far greater than hers, but..."
"I must see my sister's gems!" the Sun said. "Why can I not have gems of my own?"
"Perhaps you can," the god said. "I know a way you may be able to borrow your sister's gems, but I will need to talk to your sister on your behalf."
"Oh, if only I could talk to my sister myself!"
"Oh, there is nothing easier, Sun," the god said. "I know exactly the way to do that."
"You do?"
"Yes. Give me a piece of your heart. I will find a beautiful pony, worthy of you, and give her that piece, and you will be born within her. As a pony you will be able to look at your sister and her gems whenever you wish to stay up at night, and you will be able to speak to her."
"Oh, god of breaking rules, that sounds like a wonderful idea. I will give you a piece of my heart. Go forth and talk to my sister about my borrowing her gems, and when you find a worthy mare, give her my heart and let me be born in a pony."
"I shall go right away," the god said, and went to visit the Moon.
"Oh, Moon! I have just come from your sister the sun. She misses you dearly!" the god said.
"And I miss her," Moon said softly. "But we can never share the sky together, so we can never see each other."
"It's too bad; you missed some wonderful stories," the god said. "She was telling me all about the things she sees the ponies doing as she watches them in the day."
The Moon felt jealous. "I never get to see ponies," she whispered. "They're always sleeping when I'm out. I wish I could watch the ponies too."
"I know a way you can do that, Moon."
"You do?"
"Yes. I am the god of breaking rules. I can break the rule of night and day for you and allow you to come out in the day. Then you would be able to see all the ponies!"
"That would be marvelous! I would love that!"
"But I would ask of you only one small favor in return. My heart is broken, for my beloved is dead. She loved to look up at the night sky and see your beauteous face, and whenever I see you, I remember the times my love was happy. Please give me a small piece of your heart, Moon, to carry with me so that I may remember my love's happiness, and I will show you the way to see ponies who are awake."
"That seems a small price," Moon said, and gave the god of breaking rules a small piece of her heart.
Then the god of breaking rules broke the rule of day and night. Moon came out during the day and saw the ponies of the world at their daily business. As she moved to get a better look, she saw her sister. "Sister! Sister Sun! It has been so long!" she said, and ran to give her sister a hug.
When Moon hugged her sister, she blocked her sister's light from the world. Sun disappeared, only visible as a brilliant corona of light around Moon's edges, and Moon's gems, the stars of the sky, appeared all around Sun. So Moon was able to see the ponies, and Sun was able to borrow her sister's gems, and both were able to meet each other for the first time in many years. This was the first eclipse. And that is why you should not fear an eclipse, for it is only the sisters embracing each other.