"Twilight Sparkle, my dearest acolyte,
I hope this long letter finds you in good health. You have expressed curiosity your whole life for the ancient secrets. I know much of what caught up with my sister and I from times long past has left you with many unanswered questions. You have also, as of late, been concerned about your age and that now, your years approaching three digits, leaves you little time left to learn.
That is something that has never ceased to astonish me about you. Your thirst for knowledge in whatever form it may come.
It is time now, in the time you have left, to understand why I kept the old knowledge from you. I have of course let slip certain details about the distant past. Your discovery of the book holding the tale of my sister's fall was no accident. I am no goddess, as you know. There were times when I thought no hope remained. When I had to remind you of the beautiful letters you wrote me to inspire in your heart the strength to rally your friends, the Embodiments of the Elements of Harmony and defeat Discord. Or when Luna and I became trapped by the Dark One. Or the long-standing peace you settled with the Griffons which lasts to this day.
But know that the Equestria you know and love today was brought to where it is by nothing less than the blood, sweat and tears of millions of ponies prior and of Luna and I.
It has been asked, by those who do not understand us that they do not understand why we are called 'Princesses'.
Pony historians call them The Ancient Times. But Twilight, I can close my eyes and recall the... horrors. In those days, the royal family of the Alicorn ponies all struggled to maintain civilization and order. We Alicorns had mastery over the body, allowing us to keep eternally youthful. As such, once Everfree City was filled, we saw no need to continue reproducing.
Then... Discord came.
Forget what little you know about him, what little I dared tell. Discord was a monster. There is no point telling you how he came to be. For some magics are better off left unknown.
We perished. All of us. Only my sister and myself remained. But our mother, the red-maned queen whose name I dare not utter for fear of losing even more precious shreds of my heart, visits us so often in our dreams that we believe, somewhere, she lives. Yet without absolute proof, we cannot bear the heartache to call ourselves the Queens of Equestria. So until we find her, flesh or bones, we are the Princesses.
Hearth's Warming occurred when Luna and I were chasing Discord to the darkest ends of the world, well beyond the boundaries of Equestria. We had freed the ponies of Earth, Horn and Wing from Discord's influence and allowed them to live in peace for once. Of course... as the story of Hearth's Warming told, the three tribes were still reeling from his touch of madness and were disharmonious.
It was asked of us why we train gifted unicorns. If we were training heirs apparent. Oh, we have heirs of a sort. The remaining bloodlines of the creations of the Alicorns... Earth Ponies, Pegasi and Unicorns. Your friend Rarity met the heir of the original Unicorn bloodline, that sad boy, Blueblood. He more or less changed his ways after I sent him a special letter and box of Joe's donuts. You remember, don't you?
But I digress... I was talking about why someponies believe we take students on to train as heirs.
This would bring much joy and relief to the hearts of my sister and I, the sort you would not comprehend even with the golden heart you have, my once-pupil.
The problem is, even with your magical talent, nopony other than my sister and I can raise the sun and moon. Nopony can rule properly without understanding the wearisome burden that absolute leadership carries. There would be corruption and downfall. This lesson we learned from the Elder Ones. Those who walked on two feet. Everything they were became what we are today. We still see their hands... yes hands, not hoof or claw or talon... in everything. From teacup design to books.
That is why I cannot afford to allow my emotions to get the better of me.
My beloved little sister let slip her heart and the cost was catastrophic. Everfree City was utterly annihilated, the old castle pulled apart by the land itself and the lives of thousands of ponies were snuffed out overnight. But understand Twilight, the creature that destroyed Everfree City and the old castle and killed so many was *not* my little sister.
To be honest... Luna was the lucky one. She slumbered for the most part, in her prison on the moon. But I, my student, had to endure a thousand years seeing to my sister's duties. Some called me a tyrant vying for my sister's throne. They know so little... What matters is that I managed to keep the balance in spite of the wearisome madness that threatened to consume my mind as it had Luna's.
Now that my sweet, beautiful little sister is back, I can finally take the time to reflect on myself.
Heavens help me, I feel so tired... So very tired...
But I *cannot*, I *WILL* not abandon Equestria. Too many have laid down their lives and we sisters have spent too many centuries forging it into a place where comforts are plentiful, work is noble, smiles are plenty and warmth is never far from anypony's heart.
No, dear Twilight, there can be no heirs, for there are none yet who can do what we do. If we do, then I will give them the reigns of my precious, beloved Equestria and find someplace quiet and solemn to live a simple, humble life. Or perhaps finally allow myself to pass as well, that we might be reunited.
But for such an even to come, I hold no breath. In all honesty, I do not believe there will ever be anypony who can rule with peace and love. Nopony who can truly appreciate this land as much as we do.
So I am committed to protecting and caring for this land for the rest of my eternal life.
I sound weary, and believe me my student, I am... but Twilight, you and your dear friends allowed me to smile genuinely for the first time in the millennium since my sister lost her way with your parties, your correspondence and learning to speak to me like a normal pony rather than a princess.
But you will soon pass beyond where I can reach and since your friends are all tied to you, they too will pass on the same evening. You are six of the greatest heroes Equestria has ever known.
I know what you will say. That myself and Luna should be included as heroes.
But my beloved Twilight, we are not heroes.
We are but pillars on which a heavy burden lays.
Wherever you go, Twilight, you and your friends will make it a better place.
I am a sorrowed to see you leave, but in your brief, precious flicker of a life, you have warmed the ground at my hooves and brought a smile to a weary soul.
I hope this letter finds you in good health, my acolyte. For when the hour that is on both our minds finally arrives, I have more tears to shed than I think I can stop.
You have shown this ancient, broken old mare that these endless days of vigilance are and have been worth it.
Please do not think that I wish to send you off with more baggage than you arrived in this world with. I just needed to bare my soul to *someone*, and I knew that you of all ponies would be able to understand.
Thank you, my dear, precious, golden-hearted Twilight...
Your mentor, your regent and your eternal friend, Princess Celestia."