Dear Twilight Sparkle,
You recently asked me how I would define "evil," while writing an essay on moral employment of mind manipulation spells. Your question, I admit, gave me pause. I answered you with a letter saying that what defines evil varies from pony to pony. That is true—but it ignores your question, one I feel you have a right to ask. My definition for evil is unfortunately not very simple to explain, but, for your sake, I will try, so that when the time is right I can share with you one of your mentor's many, many secrets.
Evil and Good. I can't remember the days when I used to believe in those. I can only remember that they existed, in that way that one can know they've lost something but not know what it is they've lost. The tragedy of my case, however, is that I know exactly what it is I've lost. I cannot judge any longer, not in truth. For a ruler, that is a terrible burden to bear. My power has not decreased in any way—I can condemn, I can punish, I can pass sentence, but I cannot judge. These things are not judgement. They are the consequences passed out to those who have been judged. What could be more false than a punishment for wickedness not truly perceived?
I suppose the pony who gave the punishment.
There are many examples of times when I have acted when there was no impulse to act, but only a few stand out in my long memory. You know all of them, too, which will be convenient to show you the point of my writing this.
There was Nightmare Moon; a spirit who my sister unintentionally built from her own repressed hatred and bitterness. She stole my sister from me. She tried to stop the sun from ever rising again. And for that, I sent her to the moon for a thousand years. Nearly every pony who knew of the event believed her an evil creature and my actions correct. But I can't call her evil, nor am I sure she deserved what I did to her. She was only a response to ignorance, to disdain, to disrespect. Her mother was loneliness, her father lack of purpose. Her identity, and what would be my sister's identity so long as she remained trapped inside Nightmare's skin, became defined by what she saw as her unrecognized work. Her only desire was to see ponies see her and know that she was the one who controlled the moon, who made the night sky beautiful, who gifted them occasionally with sweet dreams or tempered their spirits with nightmares, and bow. Whether in respect or fear, she did not care. But she never truly wanted to hurt anypony. I'll ask you this; when you and your friends headed into the Everfree Forest to stop her, did she try to hurt you? Did she use lethal measures, or even a fraction of her true power against you? I don't believe she did.
The moon does not give life, it is true. If I hadn't destroyed her, or sealed her on the moon, or otherwise stopped her, Equestria would have withered up and died. Action was necessary. But that doesn't mean she deserved it. She didn't think about what she was doing. She couldn't think about it. Nightmare Moon wasn't a rational being, and she wasn't a complete being. She had no restraint. She had no fond memories of life or of loving others. Nightmare was made of the single nightmarish fear that hung constantly over Luna like the dark shadow it would become—that she would be loathed forever for her best efforts to give the world beauty and rest. It is no surprise at all that she was little more than the desire to force recognition and get, if not appreciation, respect for her work. But I trapped her on the moon in solitude for a thousand years regardless. I would cry every night for months afterwards. Sometimes I would cry in the day, if my thoughts turned to her. Sometimes I would cry in the day and I wouldn't know why, and it would seem like there was nothing connecting what I was doing to my sister or Nightmare. Perhaps that was why I always knew the tears were for them.
Discord, too, I cannot claim to think evil. I could claim a shallow hatred for him, for his mannerisms, for what he did to me and my sister all those years ago. And his actions were often truly reprehensible. But is evil in the act, or the motive? I think the motive. When a sentient creature murders for pleasure, it is a terrible thing. When a sentient creature murders as punishment, it can often be called justice. Discord did not act out of some sadistic drive, nor did he act out of base greed. He has no purpose in his action. One could say that doing what he did for no reason is the greatest evil—I disagree. An aimless individual, for all intents and purposes, may as well be considered as a force. If an act is done, and the doer could not name the reasoning behind it, not even say, "it made me happy to do that," what do you call that doer?
Discord acts the fool. He acts the sadist. He acts the puppeteer, the intellectual at play in some grand scheme. He is neither. Both those things require purpose; Discord has none. He has no hobbies, no family, no companions, and the capacity to do anything—There is, in essence, no scale or base needs for him to understand life by. He has nothing to care about and nothing to give him connection to a normal life. He cannot appreciate anything. He can't love. He can't hate. And yet he needs purpose, as all living things do.
He wears chaos as his goal. Appropriate, given the nature of his powers. And he follows, for the most part, through. Oh, true, he focused his attentions where they would be to his advantage, namely on you and your friends. But he was, otherwise, devoted to the principles of chaos. Random. Unpredictable. Out of conscious understanding or control.
I don't know where he came from, or what he was thinking when he claimed to rule Equestria those many years ago. I knew only that he had to be defeated for a civilization to rise, as was desperately needed for ponykind. And so I did as such. I trapped him in stone. Ironically, I think he thought himself more wicked than I can now attest to. He did not resist or dodge when I assailed him with the elements. He posed, he made an external mockery of it, but he knew that the elements were dangerous and he must have at least suspected they could harm him. To pose, to let the beam fall like an executioner's axe on his neck... He must have felt, in part, that he deserved it. When he "lost"—and I in no way mean to undermine the significance of your victory, Twilight—to you and your friends, I knew he was, if not consciously, letting us win.
And as such I can't call him evil.
Chrysalis I can explain in fewer words the thinking behind my acceptance for; she does not think like a pony. The hivemind that is the Changeling colony does not think as we do. They are cold, ruthless, and collective. They have no art, and besides in the upper ranks of their biologically-mirrored hierarchal society, no thought beyond base needs and orders. She fought to conquer us for the profit of her race, though where the profit lay for a parasite species reliant on stealth and infiltration direct assault and conquest I can't claim to understand or see. She is, in my eyes, doing no more evil than I did when I tried to defend my kingdom.
In an odd, abstract way, even Sombra I can forgive. He was foolish for delving into dark magic. We cannot deny that. And yet I've done the same. And I know you have. The Sombra who would become the evil, and I won't say he was not in behavior, King Sombra was merely a curious unicorn with an unfortunate destiny. He was not evil. As for the magic that corrupted and possessed him, warping him into something that was evil... Again, can we truly call the end result that, if it was sculpted by forces outside its control, and, in this case, not the fault of even anything with thought or motive? We cannot call Sombra evil for committing a sin we too are guilty of. And even the art of dark magic itself... Can a mystic art be really simply labeled as bad, when it should be left under the control and morality of it's wielder, as when you or I wield it? I don't believe so.
And with that, I fear I've rambled too long. You understand completely what I'm trying to say, my pupil. You've always been perceptive. I can only hope you do not think less of me for it...
Your Mentor... Princess Celestia, Celestia signed. Her quill hovered down and perched itself tip in an ink container. Celestia rolled up the scroll. I wrote it. Instantly, her resolve crumpled, as though without the idea of getting it down on paper between her and the idea of sending it had no place in her any longer. I should send it. She deserves to know, Celestia thought.
But does she need to know? You've ruled this nation as a lie for many years. What's one more secret kept?
She stared at the scroll for a moment as she weighed her choices. She made no motion. There was no sound but the crackling of the fire in her fireplace.
Minutes later, she sighed, voice weighed down by fatigue. The fatigue of centuries, she thought. She stood from her floor, leaving the scroll where it was, and walked to her bed. She was so tired, after all. And tomorrow she had a meeting with Minotaur diplomats, which would no doubt demand her full attention. The decision of whether to tell her student could wait.
And it always will, her mind whispered darkly in her ear as she lay down in her bed.