"Okay, don't tell me," said Spike. "Is there a D?"
Twilight Sparkle's horn glowed pink, and the gallows she had drawn in midair with her magic sprouted a noose at the end of its rope. "One more try, Spike," she said encouragingly. "Come on, you can do this."
Spike frowned, and stared up intently at the glowing _AN_ARO_ that hovered beside the gallows. "Okay, let's see," he muttered. "No T, no E, no I, no S, no D, and no second N. There's got to be only so many things left that last letter could… oh, I know! How about a W?"
Twilight's face fell, and she shook her head sadly and kindled her horn again. A little stick-figure pony appeared in the noose, and the three empty letter spaces filled themselves in – to Spike's entire mystification, when he saw what they spelled. "'Kangaroo'?" he read. "What the hay is a kangaroo?"
"Don't you know?" said Twilight, surprised. "It's a kind of animal from the southern deserts. Jumps instead of walking, keeps its babies in a pouch… no?"
Spike sighed. "See, Twilight, this is the problem with playing Hangpony with you," he said. "It's great that you know all these obscure words, but you've got to remember that not everyone…"
Then he broke off abruptly; a queasy expression passed over his face, and he belched forth a jet of green flame, on which rode a scroll with a familiar royal seal. Twilight's eyes widened in delighted surprise; she hadn't had any idea that a letter from Princess Celestia was on the way.
"What does it say, Spike?" she said eagerly.
Spike plucked the letter from the air, broke the seal, and unrolled the scroll. "'My dearest Twilight,'" he read aloud, "'I will be surprising you one day next week with a personal visit at the Old Oak Library. I look forward to spending several hours with my faithful student, hearing more of what you've learned in Ponyville and sharing news of your old Canterlot stomping grounds. Your loving teacher, Celestia.'"
An announcement of a surprise visit, he thought. How strange. But probably wise, too, since his mistress wasn't the kind of pony to get much pleasure out of total surprises; even the modified version seemed to have galvanized her into a conscientious frenzy. "Princess Celestia's coming here?" she exclaimed. "Oh, my… Spike, quick, get some bags and clean the droppings out of Owlysius's cage! I'll take care of the chocolate sauce Pinkie spilled the other day; I know there's a spell for that somewhere…" She pulled a spell-book off the nearest shelf and started flipping through it frantically. "Let's see: 'Chocolate stains, removal of'…"
"Twilight…" said Spike.
"Or would it be under 'Stains, removal of, chocolate'?"
"Twilight…"
"Or maybe 'Of chocolate stains, removal'…"
"Twilight!"
The tenor holler penetrated Twilight's focus, and she looked up irritably at her service dragon. "Spike, why are you just standing there?" she demanded. "Next week begins tomorrow; she could be here within hours!"
"Come on, Twilight," said Spike patiently. "Do you really think the Princess would do that to you? She's been your teacher for years; she knows what kind of preparation you need for stuff like this. Probably she won't show up until next Saturday, just to give you the most time possible."
"Don't be silly, Spike," Twilight retorted. "She couldn't possibly come on Saturday."
Spike blinked. "Why not?" he said. "Isn't Saturday part of next week?"
"Of course," said Twilight, "but she said in the letter that her visit was going to surprise me. Now if she came on Saturday, that would be the last possible day she could come, so I would know that she had to come that day, and I'd be expecting her to come that day. And if I'm expecting it, then it can't be a surprise, so she can't come then. Simple logic."
"Oh," said Spike. "So the latest she could come would be Friday, then."
"Right," said Twilight.
Then she paused, and said hesitantly, "Except that really wouldn't work, either. I mean, if I know she couldn't come on Saturday, and she hadn't come by Thursday, then I would know on Friday to expect her then – so she can't come that day, either. And the same for Thursday, if I know she can't come Friday or Saturday – and for Wednesday, if I know that…"
"Well, when can she come, then?" said Spike.
Twilight's lips moved soundlessly for a moment, and she frowned. "I… don't think she can, Spike," she said slowly. "If the last possible day isn't possible, then no day is ever possible, because every possible day is always the last possible day once all the later possible days have been taken away. Even if she came tomorrow, I'd have to expect that, and expecting it would ruin the chance of its being true.
"But that doesn't make sense, does it?" she continued. "If she knew she couldn't do what she told me, why would she tell me she was going to do it? She's always told me the truth, and I know she always will – so why would she tell me something that couldn't possibly be true?" She paused, and her eyes grew wide with dismay. "Unless…"
She trailed off, and Spike had to prompt her nervously, "Unless?"
Twilight looked ill. "Unless she's decided that I'm not worthy of her truthfulness," she whispered. "She must have found out something horrible about me, and this is her way of saying she doesn't want me as her student anymore." She swallowed. "I can't blame her, I guess; I always knew I was more lucky than I deserved to be her student in the first place. And it is tactful of her to do it this way, instead of just saying straight out that she no longer wants anything to do with me. But I don't understand what could have changed her mind about me."
"Well, maybe that's not what it is," said Spike. "Maybe it's… um…" He thought frantically for several seconds, but at last had to finish lamely, "Well, maybe it's something else."
Twilight gave him a fond if shaky smile. "That's sweet of you, Spike," she said, "but it's okay, really. I'll survive, even if Princess Celestia doesn't… doesn't… I mean, look at what else I have! There's you, and my friends, and… and Shining Armor, and…"
Then her voice dissolved into a desolate wail, and she galloped to her bedroom and buried herself under the covers. Spike, hearing her muffled, racking sobs from three rooms away, sighed and made a note to himself to make something comforting for dinner that night – sweet-grass stew, maybe.
For the next few days, Twilight barely left her room, and at first refused to see anypony whatever; only when Fluttershy dropped by on Monday morning, and reacted to Spike's embarrassed rebuffs with all the crestfallen vulnerability at her disposal, did Twilight soften and let her friend break in upon her misery. That did her some good, but, come noon on Tuesday, she was still brooding on what she could have done to forfeit the affection of her beloved mentor.
"Do you think I said something unacceptable in one of my letters?" she asked Spike anxiously. "Like about Rarity being jealous of Fluttershy, I know what I should have said was that friends keep their promises to each other, and I just said secrets because I had secrets on the brain then – but the Princess would understand that, wouldn't she? She wouldn't turn me away just for a mistake like that?"
Spike, who had never pretended to know Princess Celestia as anything but a face and a name, didn't really know how to respond to this, and was much relieved when a loud rap on the front door spared him from having to. He hurried away to answer it, and Twilight continued to chew wretchedly on her insoluble dilemma.
Could Celestia have rejected her for misstating the principles of friendship? Surely not – but, on the other hoof, how could she, mere Twilight Sparkle, presume to say that? Her very reverence for Celestia involved the belief that Celestia was all but infinitely wiser than she – could make finer distinctions, perceive subtler nuances of good and bad, than Twilight could ever dream of doing – so, if Celestia judged such a punishment fitting for such an offense, who was Twilight to argue?
Spike's voice broke in on her musings. "Um… Twilight?" he called. "Someone here you'll want to see."
Twilight stifled a groan. Another door-to-door salespony, no doubt; Spike never would learn how to send them away gracefully. "Spike," she said wearily, "I don't want any encyclopedias, I can get all the cosmetics I need at the Carousel Boutique, and produce can wait until the farmer's market on Friday. All right?"
A bell-like laugh, definitely not Spike's, swelled up from the room below. "My Twilight, not wanting encyclopedias?" came a familiar voice, rich with serene regality. "What is Equestria coming to?"
Twilight was so shocked that she spontaneously teleported into the foyer; the smell of singed mane and tail filled the room, but Twilight was too preoccupied with the tall, milk-white figure in the doorway to notice. "Princess Celestia," she gasped. "You're here."
"Of course," said Celestia. "Didn't I say I would be?"
"But you can't be!" Twilight exclaimed. "I worked it out: whatever day you came, it couldn't be the surprise you said, because I'd have to be expecting you!"
"Were you expecting me?" said Celestia softly.
"Of course not!" Twilight snapped. "I…"
Then she broke off, and frowned in sudden perplexity. "Wait a minute… so then… but still, that doesn't… what?"
Celestia laughed gently. "You'll have to forgive me, Twilight," she said. "I knew when I sent that letter that it would mean several days of anguish for you – but I didn't think you could learn the lesson any other way."
"What lesson?" Twilight managed.
“The dangers of over-thought,” said Celestia. “Your faith in reason is one of your greatest strengths, Twilight – but, just because of that, you were in danger of coming to believe that you could solve any problem just by thinking hard enough about it. There have been ponies before now to whom that happened, and they’ve generally ended up as either the cruelest of tyrants or the most pitiable of maniacs – or, on occasion, both. And I couldn’t let that happen to my dearest Twilight.
“But I knew I couldn’t simply warn you of the danger; to you, that would have sounded like an attack on reason itself, and you would only have grown more defensive of its sufficiency. The only solution was for you to live out a scenario in which thought was, by the nature of the case, self-defeating – where the very act of thinking things through was simply a more agonizing route to the same result as if you had done no analysis at all. And I didn’t think, somehow, that Ponyville would provide you with a scenario like that on its own – so,” she concluded with a smile, “I gave it some help.”
Twilight stood stock-still for a full minute, as all the implications of this sank in; then she looked up at her teacher with eyes that brimmed with wonder. "Why me, Princess?" she said. "I'll never be anywhere near as wise and good as you are; why did you want me for your student?"
Celestia smiled again, secretively and a bit sadly. "Oh, I have my reasons," she said. "But never mind that now, Twilight. Why don't you have Spike fix you some lunch – you look truly famished, if you don't mind my saying so – and then tell me some more about your encounter with this Trixie pony? I really am dying to hear the details of that…"