Equestria is a wondrous nation of friendship, harmony, and convenient magic. Eras have passed under the watchful eye of the princesses, and the ponies of the land have thrived in the environment provided for them. In fact, they have been almost blessed with such a peaceful and prosperous way of life that the realities and dangers of the world in which they live are almost forgotten to them. Most struggles are resolved within a day, tops, and the easy pace of life has become the norm. For the citizens of the land, this is no bad thing, and in Equestria, it is practically a standard.

Twilight Sparkle, however, is no pony to lay down and let life pass her by. The newest princess of Equestria is curious, erudite, and ambitious, and in her quest to learn more about the nature of reality, she has taken to studying all she can about the world. In pursuit of this noble goal, she spends more time with her once-rival Sunset Shimmer and co in the mirror world, talking and exploring the ways of the alternate world.

And then comes the snag. While the two worlds may share many similarities, humanity has found a way to push forwards with an eagerness and vigour that even the Princess of Friendship finds amazing, and in doing so, confronts the mare with some uncomfortable questions, all of which she seeks to answer for the betterment of ponykind.

Except for "what is beef?" and "where does glue and leather come from in this world?"

Equestria probably wont benefit from discovering those, and Princess Luna would have to defer most of her workload to a certified therapist.