What is the oldest language known that we have full grasp of?

[Dragon27]

Then, could you propose a definition that, in your opinion, would make sense? I don't really have a good sense of how to go about this, so I'm happy to hear suggestions.

I would have already tried to propose a definition if I had one (that's why I asked for examples, to at least try to establish some baselines). My first gut feeling was to say that we don't have a 'full grasp' on any ancient language whatsoever given how much it takes to learn a modern one to claim that (in some sense). So I don't think that I would have even tried to ask this question. The best alternative would probably be trying to figure out to what extent we do know any of our "classical" ancient languages.
Learners of modern foreign languages speak in these languages by trying to copy native speakers. If there is something that you want to express in a non-native language, ideally you should have already heard a native speaker expressing the same or very similar thought, so that you could recall it and change it a little bit for your own use. Otherwise you're going to need to make some expressions of your own and hope it turns out to be understandable. What can we do to amend the situation and improve? We can ask a native speaker to correct us and suggest a better way to say the thing we wanted to say (alternatively, we can just google it), or we can keep getting input in our target language (and the available content in most of the languages people are prone to study is usually large enough to last one a lifetime) and getting new expressions, that will, hopefully, cover our needs.
Ancient languages are not amenable to these strategies. We don't have native speakers, neither we may have enough input from which we can pick up the required phrases. According to Spencer McDaniel (in the context of ancient writings):

It would be possible to read the entire surviving corpus of Greek and Roman writings within about eight months if you were to do it as a full-time job.

So we can only go so far, until we essentially start inventing the language ourselves from what we've already learned of it. I do think that for some languages (like Latin or Greek) our personal inventions (if done with proper care) wouldn't be too incomprehensible for the actual native speakers of those languages, but would they consider them natural?

I would say Latin to be honest. The literature alone that we were able to conserve is incredible on its own. Ancient historic documents, poetry, legal documents, memoirs, graffiti. Plus it was heavily used during the Middle Ages up until the end of the modern era albeit with slight changes. Yes, there are still tons of materials out there in other ancient languages but I think we have enough Latin (including Harry Potter books) where it could make a comeback if it wanted.

There were no native speakers of Latin (i.e. Romans) during Middle Ages (or later), so they had to invent their own stuff (especially vocabulary). There was a wide variety of styles, many of which deviated from the classical language (and later, during the Renaissance, there was a movement to return to the classical form and purge the Latin from all the medieval innovations). What about Greek, though? It didn't disappear during the Middle Ages, the Byzantine Greek is a direct descendant of the Classical Greek, and we do have preserved writings of it as well.
On the other hand, if we only want to consider the Latin and Greek of classical antiquity, then Ancient Greek seems to be in better shape. Here's a photo of a complete set of all the books in the Loeb Classical Library:
https://qph.fs.quoracdn.net/main-qimg-b ... 70e714f24e
The books with the green covers are in Greek, and the ones with the red covers are in Latin. You can see that the Greek collection is almost twice as big as the Latin one.

[Iversen]

Well, actually there were some very young novices in the monasteries who got their Latin from such a tender age that you must accept them as native speakers - of Medieval Latin with a regional twist of course, but still Latin. And nowadays there are second language learners who speak it fluently using our best guess at the original pronunciation. I'm fairly sure that for instance people like Miraglia or the late Reginald Foster could have a pleasant discussion with a revived ancient Roman. Maybe there also are people who could do the same with Classical Greek or Sanskrit, but I just don't know any specific names since I haven't studied those languages.

When we get further back the scarcity of information about pronunciation and the lack of silly texts in the vernacular and dubious writing systems would make similar feats much less likely. Of course you can get something out of historical lingustiocs, and one linguist (was it Schleicher?) once wrote an anekdote in recontructed Protoindoeuropan - but since he did it science have moved ahead and his version now seems outdated. I do think that some scholars might be able to produce a pastiche of a high level Babylonian text, but then it would be constructing it rather than just expressing themselves freely - and with little regard for the pronunciation.

Actually I have written short fragments in Ancient French and Ancient Occitan and even Anglosaxon myself (and well, let's just add Nynorsk), so I know how you can laboriously construct a text if you have a vast store of passive knowledge about the old language, but it has nothing to do with free language production, and (unlike one of teachers at the university!) I couldn't have a discussion in any of the languages I mentioned.

[Beli Tsar]

According to Spencer McDaniel (in the context of ancient writings):

It would be possible to read the entire surviving corpus of Greek and Roman writings within about eight months if you were to do it as a full-time job.

This is only true on a very narrow definition of 'Greek' and 'Roman'.
For instance, with Greek, it means proper classical writers. It ignores the vastly larger volume of Koine Greek (not that much later!) let alone the long tail of Byzantine Greek.
We have reams of Greek like this, including lots of colloquial daily Greek - little letters, notes, graffiti, dialogues etc. The tlg index of Greek literature (see http://stephanus.tlg.uci.edu/) has more than 12,000 records, about 110,000,000 words, but that's excluding the vast volume of 'non-literary papyrii', which are very interesting to a language learner. Good luck reading all that in 12 months, even if you drop the Latin.
We have loads of full grammars of the language written by native speakers. There are even several ancient books of language-learning dialogues, the The Colloquia of the Hermeneumata Pseudodositheana, describing everyday life situations, with parallel Greek and Latin translations - ancient Assimil. You can get them on Amazon if you have a couple of hundred pounds spare, or whatever your local currency is.
We know well enough what the pronunciation was, too - yes, there are a few quibbles, and I'm sure you'd sound pretty off to the locals if you went back in time, but it was a widely used language with lots regional variation, so I'm sure they would cope.
In other words, I'm sure Greek qualifies for the OP's 'full grasp', though you might want to go for the slightly later Koine: we don't have that kind of grasp of Attic.

There are far more good modern speakers of Latin than ancient Greek - but that's for very different, cultural reasons, partly because most classicists focus almost exclusively on the older, 'purer' dialects. If you wanted to work hard at creating some new native speakers, it would be quite doable.

(Edited due to many incompetent errors and much mistyping).

[Dragon27]

This is only true on a very narrow definition of 'Greek' and 'Roman'.
For instance, with Greek, it means proper classical writers. It ignores the vastly larger volume of Koine Greek (not that much later!) let alone the long tail of Byzantine Greek.

Yes, of course, that's what I meant - Classical Greek and Latin.
It's just that I have some misgivings about trying to extend the brackets too far and mixing multiple ages of the language (even if they are not that far away in terms of mutual intelligibility). Many people like to refer to this vast array of Greek varieties from Ancient to Modern as a single language. That is stretching the concept of language too much in my opinion. I personally prefer to view it as a dialect continuum (but in time, rather than in space).

The tlg index of Greek literature (see http://stephanus.tlg.uci.edu/) has more than 12,000 records, about 110,000,000 words, but that's excluding the vast volume of 'non-literary papyrii', which are very interesting to a language learner.

Thanks for the interesting resource.

In other words, I'm sure Greek qualifies for the OP's 'full grasp', though you might want to go for the slightly later Koine: we don't have that kind of grasp of Attic.

Good, if that's the case. Koine Greek has been a very important language variety through the later ancient period in the Mediterranean world. But, as you said, Attic Greek (which is what usually meant when talking about Classical Greek) isn't preserved that well. Though, probably, well enough to be able to have conversations with (at least, educated) speakers from Classical Greece (and learn the rest with immersion).

[Lycopersicon]

If by having a full grasp of a language we assume that the existence of native speakers is a prerequisite then I would say that Persian is the oldest language that we have a full grasp of. 


Modern Persian as it is written and spoken today is nearly identical to the language that emerged as early as the late 8th century in central Asia.

A Persian speaker could literally travel to 10th century Bukhara and buy a loaf of fresh, tandour-baked flatbread off the street

Classical Persian literature is extremely abundant and covers a wide range of genres from history to poetry, anecdotes, philosophy, medicine, lexicography, biography, art theory, literary criticism, cookery and travelogues. Even the oral folklore is relatively well documented. Persian essentially functioned as one of the world’s most ubiquitous lingua franca for almost a millenium so there are tons of manuscripts all over Eurasia, too.

Arabic and Tamil also have a competitive profile but the severe diglossia that affects these languages makes them somewhat less relevant. 

Greek is a strong candidate as well, for sure. However the different stages of the language aren’t mutually intelligible it seems

[Beli Tsar]

This is only true on a very narrow definition of 'Greek' and 'Roman'.
For instance, with Greek, it means proper classical writers. It ignores the vastly larger volume of Koine Greek (not that much later!) let alone the long tail of Byzantine Greek.

Yes, of course, that's what I meant - Classical Greek and Latin.
It's just that I have some misgivings about trying to extend the brackets too far and mixing multiple ages of the language (even if they are not that far away in terms of mutual intelligibility). Many people like to refer to this vast array of Greek varieties from Ancient to Modern as a single language. That is stretching the concept of language too much in my opinion. I personally prefer to view it as a dialect continuum (but in time, rather than in space).

Fair enough! You could certainly make the case they are substantially different dialects - dropping pitch accentuation, a noun case, etc.etc. In that case, Koine is another good candidate for earliest language. Of course, it's also useful for back-filling our knowledge of Attic. So much literature written during the 'Koine' period is in good Attic by people who read Attic well. So many authors writing good 'Attic' are not included in the Attic canon because they wrote at the wrong time.

Good, if that's the case. Koine Greek has been a very important language variety through the later ancient period in the Mediterranean world. But, as you said, Attic Greek (which is what usually meant when talking about Classical Greek) isn't preserved that well. Though, probably, well enough to be able to have conversations with (at least, educated) speakers from Classical Greece (and learn the rest with immersion).

Yes, I'm sure that's true. Pronunciation and pitch accentuation would be a real problem. But I'm sure if you also had a good knowledge of colloquial Koine it would help expand your vocabulary.

[Beli Tsar]

Modern Persian as it is written and spoken today is nearly identical to the language that emerged as early as the late 8th century in central Asia.

A Persian speaker could literally travel to 10th century Bukhara and buy a loaf of fresh, tandour-baked flatbread off the street

While I don't want to get into a dangerous political topic (!) to what extent has the influence of Arabic changed that? Hasn't the number of loan words and grammar increased substantially since then?
I still remember my surprise when I realised that 'advanced Persian grammar'in textbooks turned out to be 'basic Arabic grammar for learners of Persian'.

[Lycopersicon]

I'm not an expert in any way so I'm not going to speak from a position of authority here, but I believe that modern Persian was already quite heavily arabized by the time it had started to reassert itself as a written, stately language.

That would make sense because, after all, Persian only really started to take off after the golden age of the Abbasid caliphate.

Now, what's truly fascinating is that it is quite likely that modern Persian was already firmly established as a lingua franca before the muslim conquest. Scholars suspect that middle Persian (Parsi) was essentially moribund as a vernacular language by the last decades of the Sasanian period.

Indeed, Dari (that is to say the earliest, unattested version of modern Persian) was possibly the de facto dominant language of Ctesiphon. It had also probably started spreading eastwards to urban central Asia where it was to dislodge Parthian, Bactrian and Sogdian in the following centuries.

https://iranicaonline.org/articles/dari

Regarding Arabic grammar, yes, of course. It's quite helpful to have a basic grasp of Arabic morphology in order to truly understand the literary register of the language. Nothing too advanced, though. I think we could safely compare that to speakers of European languages studying Latin and Greek affixes.

[Raconteur]

So we can only go so far, until we essentially start inventing the language ourselves from what we've already learned of it. I do think that for some languages (like Latin or Greek) our personal inventions (if done with proper care) wouldn't be too incomprehensible for the actual native speakers of those languages, but would they consider them natural?

Okay, so for the sake of looking at the other side - what would be the oldest language that we have absolute, complete (zero compromises) understanding of?

I'm guessing it would have to be a language that continues to have native speakers, alive and well, but older than other currently used languages.

[Dragon27]

Okay, so for the sake of looking at the other side - what would be the oldest language that we have absolute, complete (zero compromises) understanding of?

I'm guessing it would have to be a language that continues to have native speakers, alive and well, but older than other currently used languages.

Wait, an old language, that we have zero understanding of, but it still has native speakers? Why do we have zero understanding of it, then? Is it some kind of secret language, that we only the name of? I sense some unspoken assumptions in the question.

Other than that, there should be some extinct language mentioned in historical documents, that we have no surviving fragments or inscriptions of. It must be pretty obscure, though, since we usually have interest only in those languages, that left us at least with some examples of text. Or, maybe, the language of some undeciphered script, like Linear A (a great candidate, btw).