The prophecy of Nightmare Moon's return has been told from generation to generation. Many ponies came to regard it as nothing more than a mere legend. There was, however, a second prophecy. One that was not known amongst the common ponies of Equestria, for its meaning remained a mystery, even to Celestia.

"When night and day collide, peace will be restored, and the Spirits of Harmony will return true balance to Equestria."