Eternal English

"Ye knowe eek that in forme of speche is chaunge

With-inne a thousand yeer, and wordes tho

That hadden prys, now wonder nyce and straunge

Us thinketh hem, and yet thei spake hem so."

- Geoffrey Chaucer, 600 or so years ago

All languages are always changing, all the time, so long as someone is alive to speak them. This is the basic idea behind an entire discipline of linguistics. It means that a thousand years' difference (for example, between Old English and modern English) can make two versions of the same language completely unintelligible; another thousand (as with the 2,000 years dividing Latin and modern French) and you might not even realize they're related.

In real life, a character traveling into the distant future would literally have to learn a completely new language: even if people are still speaking what they call "English", it won't be similar enough to the character's English to allow intelligibility. In fiction, however, linguistic drift is almost universally ignored. For writers, it's a lot of trouble to translate into an ancient or imaginary language, and audiences often prefer to watch a show in their native language. Therefore, people hailing from vastly different time periods will almost always speak the language of the audience, and rarely with so much as Just a Stupid Accent (though characters from The Middle Ages or thereabouts get to speak Ye Olde Butcherede Englishe).

In many future settings, the writers will try to balance this out by throwing in a couple of new slang words. Others will try to attribute this trope to the advent of recording technology. This may or may not turn out to be the case: after all, we are discussing tropes and memes on a wiki hosted on the web. Someone from the year 2000 wouldn't understand some of that sentence, while someone from 1990 would understand almost none of it (hell, a good number of people today still wouldn't understand it).

In some cases, a work will be set in a distant time period, but the characters don't encounter any time travelers, read modern books, or watch modern movies. Settings like these are actually invoking Translation Convention.

The absence of Language Drift. Compare with Aliens Speaking English.

Anime and Manga

 * In Fate/stay night, Servants are summoned from the distant past and seem to have no problem conversing fluently in modern (even accentless, in the anime) Japanese. This is probably a case of Translator Microbes too, since most of them aren't even from past Japan, instead hailing from places as distant as England. Ninth century England, no less, where they spoke a language even most modern English speakers would be hard-pressed to understand.
 * Inu Yasha. Kagome falls into around the year 1550 and has no trouble understanding Late Middle Japanese. Inuyasha has managed to come to the present without any trouble either.
 * The English translation has Kaede use the archaic thou and thy, hinting at the language changes. 1550 is only five decades away from the start of Modern Japanese, so it's understandable that Kagome wouldn't have too much trouble.
 * There is an "Outer World" in Slayers that has been blocked off by a magical barrier courtesy of the Monster Race for at little over a millennium, hence two different cultures: the "Inner World" (i.e the main setting of the series) thrives on magic, and Word of God put out that everyone in it speaks the same language. The "Outer World" has little access to magic and thrives on technology instead, and has peoples in various types of environments, including a scant amount of primitive tribes. The third season of the anime has the main party go to the Outer World, but unless one member of the group has a translator on them, it would be unlikely that the Outer Worlders would speak the same language (whatever the heck it is) as they do. This problem doesn't arise in the novels because Lina and Gourry stay in the Inner World for the entire time.

Comics

 * Lampshaded in The Return Of Bruce Wayne #2: a man in Puritan times says to time-shifted Bruce Wayne: "All agree thy speech is stranger even than the Dutchman's here. As if the King's English were not thy native tongue." Which is understandable, since they all speak (an approximation of) 17th century English, while Wayne speaks modern English.
 * A New Mutants story involving time-travel brought them to the middle ages where Wolfsbane (Rahne Sinclair, aged 14 or 15) was able to converse fluently with Robert the Bruce just by virtue of coming from Scotland while her teammates weren't. There was no indication that Rahne had learned Middle English or indeed Scots Gaelic (should Robert have even spoken the latter).

Eastern Animation

 * Played with in The Mézga Family, a Hungarian cartoon from the 70s. The titular family, living in the 20th century, manages to contact a descendant called MZ/X, who lives in the 30th century. At first they don't understand a word he's saying, as MZ/X speaks "new Hungarian", which is just modern day Hungarian with EVERY word abbreviated to one syllable. Thankfully he has a telepathic helmet he can put on when he wants to talk to his ancestors from "the atomic dark age", as he calls them.

Film

 * Lampshaded in the third Teenage Mutant Ninja Turtles movie, when the Turtles in Feudal Japan find that everyone they talk to knows English, which had been introduced to Japan only a few years earlier.
 * The film version of Timeline has this, with medieval French and English soldiers speaking the early 21st century version of their languages perfectly so that the English troops have no problems communicating with the modern-day heroes.
 * In the 1960 film version of The Time Machine, the Eloi speak perfect English over 800,000 years in the future.
 * Justified with the Morlock leader through the use of Psychic Powers.
 * WALL-E. Of course, there's a good reason why humans haven't really changed language a lot in a few centuries.
 * Planet of the Apes. It's 2,000 years in the future, and the apes are still speaking perfect English. Although they don't call it that...Cornelius just says it was the language taught to him by his father and his father before him.

Literature

 * Probably present in Bujold's Vorkosigan Saga, which is at a remove from the present in a comparable way that we are from Ancient Rome, but characters read Shakespeare and use Yiddish as a Second Language.
 * Not only the time gap, but Barayar was isolated from Galactic culture for centuries and reverted to some never specified semi-medieval level. Yet they came out of it still speaking Galactic Standard (whether that's English or not).
 * It's specifically mentioned that Barayar has four distinct language groups, English, Russian French and Greek. Cordelia at one point finds a book of poetry written in English but using the Cyrillic alphabet.
 * Justified (kinda) in Arthur C. Clarke's 3001, where sound recording technology is said to have stabilized all languages. As a result, they have changed about as much as is appropriate for two or three hundred years, instead of the thousand that have actually elapsed.
 * Clarke relied on the same justification in The Songs of Distant Earth.
 * L Sprague De Camp wrote a surprisingly funny, informative, and accurate essay called "Language for Time Travelers", where the Framing Device for the information is the travails of a time traveler having to deal with vowel shifts, abbreviation, and slang in the future. It's worth tracking down, and you may learn something.
 * Played straight in Lord Dunsany's short story The Avenger of Perdondaris where in the far future a shepherd's offer of hospitality is 'Everkike' or 'Av er kike,' badly decayed Cockney for 'Have a cake.'
 * Beautiful subversion in CS Lewis' That Hideous Strength: The bad guys have gone to great lengths to awaken the sleeping wizard Merlin, long buried in his tomb beneath Glastonbury Hill, and extract from him his knowledge of ancient magics. The project leader interrogates Merlin for hours in impeccable medieval Latin, only to get no response. They then try communicating in Gaelic, Welsh, Old English, and start running through the list of any ancient languages that Merlin might have spoken. Merlin continues to fail to respond, leading them to the conclusion that he's purposely stonewalling them. While they go off to confer as to how to negotiate with him, our protagonist sneaks in and randomly greets Merlin in normal modern English, and, of course, Merlin begins a friendly chat with him. It transpires that the real Merlin actually woke up and fled the scene hours ago, and the man they've got is just a random homeless guy who wandered into the site and thinks everyone around him is insane.
 * Played completely straight in Anne McCaffrey's Dragonriders of Pern. Despite taking place hundreds of thousands of years in the future, rhymes and puns still work in English, the entire planet speaks one homogenous language and ancient documents from the original colonization of the planet are completely readable by the modern characters. Additionally, a trip back in time reveals no linguistic difficulties whatsoever.
 * However, it is noted in later books that both the dolphins and AIVAS have trouble understanding/being understood.
 * Also, Robinton is distressed to discover the language has altered at all, saying that it's the job of the Harpers to make sure the language doesn't change.
 * Played straight in Ken MacLeod's Learning The World. The book takes place 14,000 years in the future, by which time it seems virtually certain that English will have changed drastically, in the unlikely event that anything that could be called English still exists at all. Despite this, an important plot point hinges on the fact that the word "bug" could mean either "insect" or "spying device".
 * JRR Tolkien was a professor of linguistics and fully aware how unrealistic this trope is, but he used it anyway with the (roughly) 500-year-old Gollum in The Lord of the Rings. Averted with the speech of the Rohirrim and its distant relation to Hobbitish (which was now mostly the Common Speech, the "Koine Greek" of the West of Middle-earth).
 * Actually, we might be dealing with a Retcon attempt to avert it. The appendices are the ones making Gollum 500. In fact, they specifically mention events which make it possible for him to be 500 - like the Hobbits temporarily returning to Anduin around that time while Sauron was banished, but the book itself seems to imply he's closer to 2000 - and the Silmarillion states explicitly he's a thousand at least (the Ring was stated to be found while Gondor still had kings).
 * Rohirric is represented (via Translation Convention) as Anglo-Saxon, to show that it's a related but very archaic-sounding tongue. Also, the language of the Men of Dale is Old Norse.
 * It is also explicitly mentioned at some point that the text of the Rings books have been *intentionally* rendered as Modern English, even though the different ages and regions would have had different dialects and (to an extent) vocabulary. Apparently, this is done to make it easier for a modern reader to understand.
 * Played ridiculously straight in Honor Harrington, where everyone speaks Standard English, unless they happen to represent a specific culture/country in real-world Earth. In which case they'll supposedly speak that language and dabble it into their Standard English that they otherwise speak all the time. It's stated that sound recordings have slowed linguistic change to a crawl. Enough that Honor has no problems reading C.S. Forester's Horatio Hornblower and the only problem she has is in dealing with the archaic units of measurement.
 * In some places it is clear Translation Convention: The Republic of Haven speaks French, the Andermanni speak a bastard German-Chinese language, San Martin spoke Spanish until the Republic of Haven came in. Most language issues are handwaved due to good translation software.
 * In another David Weber book, The Apocalypse Troll, it's somewhat subverted -- a character from 400 years in the future is stranded on modern Earth. It's stated that the advent of widespread sound recording pretty much stabilized the language, but she still has a tendency to slip into incomprehensible future slang (generally leaving out syllables in confusing places: "Mister" becomes "Ster", for example).
 * Addressed in David Severn's 'The Future Took Us' in which the protagonists only gradually realise the locals are speaking a futuristic version of English. "Bread" has become "brade" and "man", "mun".
 * Addressed in Leo Frankowski's Conrad Stargard series. When Conrad goes back in time to 13th-century Poland, he realizes how lucky he is to be there, where the language hasn't drifted very much in 700 years, as opposed to England, where he would be completely incomprehensible.
 * Frankowski tends to forget that the characters are supposed to be speaking Polish and not English so to a Polish person reading the books in English some of the conversations make no sense since they use English puns or language conventions.
 * In the Czech sci-fantasy book Divocí a zlí (Wild and Dangerous), the protagonist (who in the backstory comes from a post-apocalyptic future, and yet understands modern Czech) ends up helping Alfred the Great fight off some Danes and Swedes. And has no problem understanding and communicating with the locals. To put into perspective, Beowulf was written somewhere around that time.
 * Justified in the Commonwealth Saga/Void Trilogy, where regeneration allows essentially eternal life - so the centuries old aristocracy maintains the general vernacular.
 * Played straight with Eternal Russian in the Noon Universe novels by the Strugatsky Brothers with astronauts in STL starships that move at near-light speeds and return to Earth a century or two later. Nobody ever mentions any linguistic problems. Granted, nobody actually returns, say, a thousand years later, but there should still be noticeable changes.
 * The same happens in the Time Travel segment of Monday Begins on Saturday where an Antimatter-powered relativistic starship leaves Earth in mid-21st century and returns several thousand years later. Similarly, the girlfriend of one of the astronauts opts to become a Human Popsicle and is thawed out around the same time. None of the 21st-century characters have any problems communicating with future humans. Of course, the novel also have Aliens Speaking English (in another galaxy, no less).
 * Return From the Stars mostly plays this straight, though after 127 years there's some Future Slang, and there are scrolling ads (?) displaying confusing words that sound vaguely like corporate trademarks.
 * A particularly bad case in Sword of Truth. The High D'Haran (their Latin) has many dialects from different times, despite being mainly a scholars' language. However, the New World and the Old World have the exact same common language despite being separated for 3,000 years.
 * In Edmond Hamilton Star Kings duology, the language of the future is based on English, and can be learned quite fast by a modern man. Quite reasonable - except we are talking about 2000 centuries in the future.

Live Action TV
"Troi: But you spell knife with a K.
 * In Stargate SG-1 and Stargate Atlantis, there are cultures that lived thousands of years before English was born that speak it flawlessly.
 * SG-1 began with people on other planets speaking different languages, mostly based on old Earth cultures. By the second episode they realized it wouldn't work with only one main character (Jackson) able to speak to the people, so it was changed.
 * In Sanctuary Will mentions this as evidence of why three woman claiming to have awoken from hundreds of years of sleep have to be delusional - they all speak perfect English.  In the first episodes Helen and John's mode of speech is a clue as to their shared origin. Their English is perfectly comprehensible, but slightly archaic and formalized. They and Tesla have all exhibited some distaste for modern conventions of the language.
 * Good luck picking up on the fact that Tesla is Serbian, given his near-total lack of an appropriate accent even in flashbacks. The only time this is ever mentioned is when the British government requests they stop and do it for their country, prompting Tesla to mention that he's not British.
 * Played straight in Firefly: despite taking place roughly 500 years into the future, the only differences between their English and ours is some Future Slang and non-standard grammar. Bilingualism in Mandarin Chinese is shown to be widespread, although the actors understandably struggle with the pronunciation.
 * In the Star Trek: The Next Generation episode "The Big Goodbye," Picard was wrestling with the difficult Jarada language, and we got this gem:

Picard: I spell knife with an N. But then I never could spell."


 * For those familiar with the Universal Translator, but not the episode in question, the reason why this is even an issue is because the Jarada are notoriously formal and bent on etiquette when approached by other races; the last encounter with a Federation ship was 10 years before Picard's try, and when that captain mispronounced one syllable in the greeting they opened fire and broke off all diplomatic ties.
 * On Babylon 5, the official language of the Earth Alliance is English. A Translation Convention is in effect, but it doesn't explain how the characters can get away with verbatim quotes of Abraham Lincoln (or, in Garibaldi's case, Looney Tunes cartoons).
 * In one episode there is a delusional man claiming to be King Arthur, they figure out that he isn't who he claims to be because he speaks modern English. Though earlier Jack the Ripper was portrayed with just a British accent.
 * In one of the few Primeval episodes involving human incursions, a 14th Century knight strays into modern London and speaks perfectly clear Essex English, as does the local back in his time whom the ARC scout questions. Despite the fact that what passed for English back then was actually closer to modern Dutch. Even the fact that the ARC's knowitalls can understand him when he speaks Latin is questionable: chances are that our pronounciation of Latin has drifted almost as much as the living languages.
 * Word of God says that this was the case in Battlestar Galactica Reimagined, which was bit of a shock for the fandom who had comfortably assumed Translation Convention to be taking place, considering that the show took place.

Tabletop RPG

 * In Rifts the dominant language in the former United States and Canada is called American, which despite the different name, is indistinguishable from Modern English. Despite the game taking place 300 years after the apocalypse, where uneducated humans live in scattered, mostly isolated communities, there have been no regional language shifts.
 * In the Phase World setting, Galactic Trade Tongue Four is in fact the descendant of the English Language, where an English Speaker has roughly a 50% chance to understand Trade Four. Mind you, so much time has passed in the Three Galaxies universe that everyone has forgotten where Earth was.

Video Games

 * Played straight in Chrono Trigger and its sequel, Chrono Cross.
 * Strangely, in Chrono Trigger's Prehistory era, humans speak broken English, using bursts of short words and phrases rather than grammatically correct sentences. On the other hand, their evolutionary rivals, the dinosaur-esque Reptites, speak perfect English. Humans are also implied to have a second language, as Ayla claims that "Lavos" literally translates from her language as "Fire Big".
 * Played straight in Skies of Arcadia. All six cultures of the world (all of them centered under its six magical, oddly-colored moons) are vastly different, and yet it seems that they all speak English/Japanese.
 * There are variations on how certain people in certain lands speak (for example, the primitive Ixa'Takan tribesmen speak in simple English, while in the Japanese version, the text boxes display katakana and hiragana only, leaving some Unfortunate Implications), but it still plays straight.
 * Halo series: 500 years in the future, humans still speak 21st-century English, complete with present-day regional accents, e.g. Californian/Valley Girl ("It's totally hiding from us!"); Australian; and Mexican-American.
 * Freelancer: Despite taking place in the year 3100, those who live in Liberty still speak American English, and those who live in Bretonia still speak British English.
 * Since we never hear anyone speaking any other language, it is not clear if they are also Eternal German (Rheinland), Eternal Japanese (Kusari), and Eternal Spanish (Corsairs and Outcasts).
 * In Warriors Orochi, everyone just inexplicably speaks modern English/Japanese.
 * The three-hundred-year time skip in the second Jak and Daxter game has absolutely no effect on the language.
 * In the present(or near present) era of The Journeyman Project, which takes place 300 years in the future, everyone has (21st-century era) American accents, even in Australia.
 * Justified in The Journeyman Project 3, where Gage (and the player) simply hears translations from Ancient Greek, Mayan, Tibetan, and Mongolian, although why a translator would include accents is a little strange.
 * In The Elder Scrolls V: Skyrim, at one point in the main quest you either have a vision of the past or travel back in time a couple thousand years. When you do this, you find that people speak the same sort of english they do in your time, though this may be a function of the vision/time travel, rather than a true case. It's fairly vague on this point.
 * In Asura's Wrath, a game with a story not constrained by reason or logic in all other aspects, Asura can no longer understand the language of humanity after 12,000 years in limbo, although he can still understand his fellow gods just fine.

Webcomics

 * In Sluggy Freelance Torg and Zoe have no problems communicating with the locals when they go back to Medieval Europe. Subverted with Berk, a man from 25 years in the future, whose constant use of future slang makes him nearly unintelligible. Even other people from his time can't understand him.
 * Xkcd subverted this once

Western Animation

 * Played straight in Futurama. In the year 3000, there are only a few notable language changes. "Ask" is now always pronounced "aks" (except when the writers forget it), and not just by rappers, and "X-mas" is actually pronounced as "ecksmass". Also, people still speak modern English in the year 50 million.
 * Meanwhile, French is an incomprehensible dead language.
 * In the 10th century, the main language of Scotland was Scots Gaelic. Despite this, the main characters of Gargoyles have no trouble communicating when they come to 20th century America. Later, Xanatos, Fox, and Xanatos' father have no trouble when they end up going back in time.
 * Parodied in a time traveling episode of Pinky and The Brain, where Brain, in his Mobile Suit Human, stumbles through all his conversations trying to remember which is "Thou, Though, Thee, Ye, They, Thine, ect" until one point he grabs a guy and just yells at him until he understands.
 * The illegal immigrants from the future that come to present day South Park speak an unrecognizable language. And insist on bilingual education.
 * In Megas XLR, humans in the year 3037 speak modern English.
 * You would suppose someone who died 1600 years ago would not be speaking modern English in Danny Phantom.

Real Life

 * Language change is a constant, which causes problems in real life -- the written form of the language tends to freeze at a certain point in development, while the spoken language keeps changing. This causes definite problems in literacy, even when merely limited to works of literature and legal documents. Eventually the literary and vernacular languages become totally different (called diglossia by linguists, Greek for "two tongues"), and later still the spoken language becomes the new written standard in place of the old one. This is what happened to Latin (replaced by Romance languages), Classical Chinese (replaced by Standard Mandarin) and Classical Greek (replaced by Modern Greek), among others.
 * This is still the case with the Tamil language of South India. The written standard is still most the same as it was in around the 14th century, while the spoken form kept changing as normal, resulting a written form that contains extra vowels and diacritics that no on actually pronounces. This is further complicated by the fact that different social classes speak drastically different dialects that use different words derived from completely different roots to represent the same concept.
 * This is also somewhat the case with Arabic, where the written language is closely based on Classical Arabic, spoken at the time of the Qur'an. Colloquial Arabic differs greatly from it and there are several spoken dialects which are closer or farther apart from each other. A common debate among Arab intellectuals these days is whether or not to change the standard language; on one extreme, you have classicizers who think that all the modern dialects are rubbish, and on the other, you have local nationalists who want to break up the Arabic language altogether. Even the middle is somewhat divided: there are some who think the situation is fine as-is, or with minimal changes, while others advocate abandoning the current standard and creation of a new one based on the educated speech of Cairo (Egyptian Arabic is more or less universally understood, and Cairo is unquestionably the center of modern Arabic-language culture).
 * Tibetan's standard orthography hasn't changed since the 1100s, and is essentially the same in all the Buddhist Tibetan-speaking regions. Amazing for a language that went from having complex consonant clusters and no tones, to having much simpler consonants and many dialects having developed tones to make up for lost consonants. (To give an example, the Dalai Lama's surname 'Gyatso' (generally pronounced chatso) is spelled rgyam-tsho natively.)
 * After the fall of the Roman Empire in the west, literate people (i.e., monks) continued to write in semi-classical Latin, while the spoken Latin language evolved into several Romance languages, though these were still considered "Latin". By the time anybody realized that what people were speaking was no longer Latin, it had become a Sacred Language in the Catholic Church.
 * Also note that thanks to Humanist and early Renaissance scholarship there was a revival of classical Latin among scholars and scientists at the expense of the way Church Latin had evolved in the early and high middle ages.
 * Also the case with Burmese, where there is a formal written language and a spoken form which is never written; they are pronounced quite differently.
 * Officially, Afrikaans kept spelling in Dutch until a few years in to the 20th century, although some people spelled phonetically before then. One reason for this is that at the time, most people (even the majority of Afrikaans speakers) considered the language to be a dialect of Dutch. Since acknowledging a dialect's status as a language would usually go hand in hand with translating the Bible into it, many Afrikaans speakers were reluctant to do so, considering it disrespectful to translate Scripture into what was then still widely regarded as an uneducated-sounding, slang-littered dialect.
 * It's also pretty much the reason that English spelling is so different from its pronunciation (many words, like name, still retain Chaucer-era spellings - it was pronounced na-meh then). Combine this with etymological spellings (homage from French), false etymological spellings (island is not from Latin insula and didn't have an s until people thought it was), and the like, and you basically get modern written English.
 * The related Scots language, though, takes a more phonetic form, in part because no universally accepted standard has existed since the eighteenth century. Scots has also retained the Voiceless velar fricative or "hard ch", meaning that many of the superfluous appearances of "gh" in English- "through", "night", "thought", etc.- are actively pronounced in Scots.
 * English gets a bad rap, but people tend to not mention that French is also very different from its written form. To an Anglophone learner, it may seem as if half of every word is silent because they represent sounds which are no longer pronounced but included for etymological reasons.
 * Many ideographic logographic written languages (such as Chinese or Egyptian hieroglyphics) remain readable at least to some degree even after millennia, because often the written glyphs change much more slowly than the spoken languages. And when these are shared for writing across languages whose spoken forms have never been related (such as Chinese with the native vocabularies of Korean and Japanese adapted to Chinese characters), written texts can be partially readable across language boundaries because of shared meaning of glyphs.
 * Only partially - maybe on the level of one or two characters, definitely not whole texts. While the written form of a character may not change much in a thousand years, just like a word its meaning can shift dramatically - 好 in Japanese means "(to) like", and in Chinese means "good". There's a poem written in Classical Chinese deliberately so that when read with modern Mandarin pronunciation, every single syllable is "shi", just with different tones - surely some of those words have long since fallen out of use.
 * Further side-effect related to the above; because the words represent concepts, not noises which are interpreted as concepts in the language they represent, "glyph" languages can be taught in any language. You will have to throw in several English language constructs (articles come immediately to mind) and tense may be indicated differently in writing, but it is entirely possible to adapt Chinese characters for English. After all, they used them in writing Vietnamese and Korean, and still do in Japanese.
 * Actually, Chinese itself did for a long time depict the sounds, not concepts. Phono-semantic compounds make up the vast majority of characters - the radical signifies the semantic category, another character is used as a phonetic indicator. Since the time when those actually could be sounded out, however, Chinese has changed dramatically, making them much less indicative. For English, it would make much more sense to develop a native system, which as a thought experiment can for example be found here.
 * The Ugro-Finnic languages of Northern Europe are an interesting spoken example. Languages like Finnish and Estonian have been separated for millennia, but still have a large amount of remarkably similar words. Finnish in particular is famous in linguistics for being a slow-mutating language, with quite a few ancient loanwords mostly "frozen" in place from the time they were originally loaned. An example of this is kuningas meaning "king", which was loaned about three millennia ago from Proto-Germanic kuningaz, of which the English word "king" is a far more mutated genetic descendant.
 * Modern Icelandic speakers often have less trouble understanding thousand-year-old Old Norse than modern Danish speakers have understanding modern Swedish speakers. It's said that Leifr Eiríksson, the first European in America, would be able to be understood in 21st century Iceland.
 * For a straight example, the page quote itself. That's obvious in some cases, of course (eek? hadden prys?), but it's even trickier than it may appear; there's at least one false friend in there. "Nyce," to Chaucer, meant approximately what "stupid" means to us.
 * James II supposedly described St Paul's Cathedral as "awful", "amusing" and "artificial" -- i.e. worthy of awe, giving pleasure and made with artifice.
 * The English formal written language remains almost unchanged from the late 1800's on, but the spoken language is almost alien to a speaker from 1700.
 * Even though it did lose its incredibly complex and powerful tense system and is still leaking cases, Russian is a remarkably slow-changing language. A 12'th century epic poem "The Tale of Igor's Campaign" is still (barely) understandable to the modern speaker, for example. Even the 9-10'th century texts (like the Novgorodian birchbark letters) can be figured out by the readers uneducated in the language.
 * Similar to the Finnish example above, Irish and Scots Gaelic are two Goidelic languages that diverged from one another 1600 years ago. Yet despite this, and despite both going through many many changes in that time, they are still mutually intelligible.
 * A subtrope of creationists is Babelists, who believe in, yes, Eternal English.
 * Hebrew is an example in that, while there are definitely obvious differences between Biblical and Modern Hebrew, one can nevertheless understand a lot of Biblical passages on the strength of a Modern Hebrew education alone. But this is kind of cheating, since Hebrew was revitalized as a vernacular in the 19th century, so it didn't have the same kind of organic growth as other languages would have.
 * For instance, students in Israel going on a field trip to see the Dead Sea Scrolls can simply read them unaided. It's helpful to think of the relation between Biblical and Modern Hebrew as similar to that between Shakespearean and Modern English.
 * The changing nature of languages has raised some issues on how to mark toxic waste dumps so that future civilisations who would not understand modern languages are not endangered by this. The proposed solutions range from plausible, like putting up obelisks with pictorial warnings on them; to breeding cats that glow when in range of radiation and hoping people associate it with danger; to launching an artificial moon over the site.
 * Of course, the real problem is that putting any sort of sign, even one depicting clear danger or death, will likely be interpreted as "Hey, there's something interesting here!" and start digging. It's like how archaeologists pay little attention to the supposed "Curse of the Pharaohs" when opening Egyptian tombs.