Ever since she stopped Sombra and saved the Crystal Empire, Twilight Sparkle has taken an interest in dark magic. Princess Celestia catches wind of her student's interests, and tells her exactly why dark magic is not to be trifled with.

Image was used with permission.

I have heard ponies say that living so long would be a curse. That it is a burden. That it can break a pony's mind. There is some truth to that. It can be hard to know that you'll always be left behind as others pass on. However, that is not the whole truth, I am also blessed. I have an opportunity to see history play out in front of me and tell future generations of the ponies behind the legends.

In audio form: http://youtu.be/mTGMfwcAcwQ

After the defeat of Tirek, Equestria is safe once more, but Luna can sense that her sister is troubled. When Celestia retreats to the starry realm of ascension in order to look upon the past, Luna joins her to discover what is bothering her.

There is now a Spanish translation of this story, courtesy of Spaniard Kiwi