Mastermind Celestia · 4:42pm Apr 10th, 2013
This is something that blew me away the moment the 3rd season ended. Remember Celestia's song. It was a beautiful song and I felt a few tears come with it. A while later I realized the true gravity of the song. It wasn't just a song of how proud she was of Twilight. It was also an epic foreshadow. "How?", you might ask.
With everything that Celestia was Orchestrating from the moment she Discovered Twilight's power. She made the school of gifted unicorns to find someone like Twilight and she obviously succeded. She said that she was watching every choice, twist and turn Twilight encountered in every task given to her. She knew about Nightmare Moon coming and most likely chose ponyville because of how close it was to the elements. This would be the first true test to see if she chose right picking Twilight. The elements returned to the world and Luna was back to normal. She gained not just a perfect student but also all six elements and Luna. She was just up six more allies. She trained Twilight constantly with different tests. Tests of magic and friendship, she challenged the other elements every now and then too. She when the Crystal empire returned she needed to purifiy the Empire, with it on the Side of good and now allies an entire civilization is on her side. She reforms Discord stating plainly that she could use his powers if he joined them. In the end Twilight rose to a new level becoming an Alicorn and Celestia says that was the intended purpose of everything she put Twilight through.
All of it boils down to the ultimate point "what is she trying to achieve?" Simple, something huge is coming. Something that would require everyone, the Empire, Elements, Discord, Luna and herself. As if putting all this together wasn't enough, did you notice that in the last season in almost every episode of the 3rd she was on some political venture. Meeting with country leaders, ambassadors and others. Why?
She seems to be preparing for a war almost... Maybe she is? I would go deeper but then I would be delving into headcanon. But if it is what it seems to be... What is she afraid of?