If you have been handed this letter by a pony soldier, there is no need for me to prove his alien origin. If, however, you come across it some time in the future, you will likely find this letter impossible to believe, and I can't blame you. I have placed Princess Celestia's hair in my safe-deposit box, and the key is in my office desk. That, and a scientific analysis of this box and the contents therein should be proof positive.