"It wasn't always that way," Applejack started to explain. "See, Celestia has a sister. Princess Luna's her name. Luna used to control the moon, but one day she caught the green eyed monster over Celestia. Thought her sister was better, loved more, 'cause she brought the light. That's when Luna turned to the dark, became Nightmare Moon. Celestia had to fight her sister, trap her in the moon for a thousand years. At least, that's how the story goes."

But there was more, of course. "We've always seen her face as the mare in the moon, but we didn't know it was all true 'til the stars lined up and she escaped. Nightmare Moon took Celestia from us, said we'd have nighttime forever. So it was up to us to stop her. My friends and I---see, we learned that we've got the spirits of the Elements of Harmony inside us. By bringing loyalty, kindness, honesty, laughter, generosity, and magic together---we'd be able to defeat her. And we did! Luna was back to herself, and we threw a big party for her. Still haven't seen her since, but I guess she's had to rest up and get used to Equestria again."