Dear Daddy,
I'm sorry you have to read this in a letter. I wanted to tell you about my amazing discovery in pony, but I'm pretty sure you'd try to talk me out of leaving home. So when you find this, I'll already be gone. Now that I finally understand what my cutie mark means, this is something I have to do on my own. I'm a big girl now, and I think my actions today will prove it.
I realize I'm leaving a lot of stuff behind. I won't be back to Ponyville to claim my belongings, so I'd like to do the right thing and leave them to my friends, and to other ponies who are less fortunate than we are. I know it's going to be hard to imagine (it used to be my prized possession, after all), but I want to give away my tiara, too. You can find it in the top desk drawer. Even though it matches my name, my tiara no longer defines who I am as a pony, and I'm finally ready to be separated from it. I'd like you to give it to Silver Spoon for me, as long as she wants it. She can have Miss Muffins too. The rest of my stuff should go to the schoolhouse or to the poor, whatever works best for everypony. I also left a note for Miss Cheerilee, basically saying I'm transferring to a boarding school in Manehattan. That way, my teacher and friends don't need to be worried about where I'm going. I know it isn't true, but I think a lie can be okay sometimes if it helps ponies feel better.
I want you to know that leaving my stuff behind doesn't mean I don't appreciate all the gifts you and Mommy have given me. I've had an amazing eleven years in the lap of luxury, and I've never truly needed anything—even though I was selfish enough to want things all the time. But that was the old Diamond Tiara. I'm ready to move past my possessions so I can focus on serving my friends and my country. Those are the things that really matter. I'm finally going to make a difference in the world, Daddy! I wish I could share with you how strongly I feel, because then I'm sure you would understand I'm doing the right thing.
Now Daddy, I'm writing specifically to you instead of Mommy because I don't think Mommy will understand any of this. I know Mommy loves me, but I don't think I can put other ponies first without disappointing her. I feel bad about that, but I know Mommy's wrong. It's right to help other ponies, and friendship is more important than anything, even money. I care about my friends, and I have a unique opportunity to secure a bright future for them. I know it's unique, because I'm 100% certain I'm the only pony with my special talent—and maybe the only pony ever! (I'm not trying to brag or anything, I'm just being honest.)
I should have taken these steps a long time ago, but I didn't know any better. I've foalishly spent so much of my life trying to help myself at the expense of others. I was always trying to make myself better than other ponies, and I kept looking down my nose at them and causing drama and sadness. Even when I tried to help, which wasn't very often, I would end up hurting them anyway. I know I've hurt a lot of ponies. I wish I could take it all back. My friends—and I'd like to think of them as friends, even though most of them were closer to enemies in the past—have been incredibly forgiving of me. I didn't deserve a second chance after the terrible ways I treated them, but they gave me a second chance. And then they gave me a third chance. And then they gave me a fourth chance. All the ponies at school have treated me like a saint when I should be a pariah (that's a fancy word that means somepony you don't talk to, like how Mommy treats Randolph most of the time).
About a month ago I decided to change my ways, and to my surprise, none of the ponies at school teased me about who I used to be. Not even once! Can you believe it? What a world it would be if everypony could act like the foals of Ponyville! I wish I could act that way. I've tried to, but it's very hard and I keep messing up. I say and do things that hurt other ponies without even realizing it until it's too late. Even though I'm trying my best, it doesn't stop me from continuing to hurt them. The worst part is I'm sure most of them don't realize how hard I'm trying. They just tell me to "stop being mean" like I'm doing it on purpose, and I'm not. Until yesterday I was very sad, because I still couldn't figure out how to fit in.
But I finally figured out what my special talent is! Now that I know, I can make Equestria a better place.
It happened during a math lesson yesterday. I know I'm not very good at math, but I understand the basics. I was looking at numbers in a homework problem and thinking about the different kinds of value different foals bring to society once they've discovered their special talents. Everypony's special talent allows them to help out in one way or another, but let's face it, some ponies' special talents are more useful than others. Kind of like how some numbers are bigger or smaller than others. But nopony has a useless special talent—that would be like the number zero, I guess.
And that's when it hit me: there are negative numbers.
Some numbers have a negative value, which makes an equation worth less. But if you move them to the other side of the equation, by subtracting their value they can make the equation worth more. Don't you see? My special talent is negative! I can provide positive value to my friends by removing myself from the equation!
I love you, Daddy. And I love Mommy too, and my friends, and even Randolph. I know there isn't anything to look forward to after this, but I'm not scared. I'm a big girl now, and I'm brave enough to do the right thing.
Please keep the ceremony private so nopony except you and Mommy knows. I don't want anypony else to do this sort of thing, because I'm sure I'm the only pony with this special talent.
Your daughter,
Diamond Tiara