The essential reason anyone is learning Ancient Greek vocab is to read Ancient Greek. Anyone taking the time to try to read Ancient Greek is likely wanting to read with comprehension. Why else bother? Whether you are aiming at the New Testament, Attic Orators, Homer, or any other body of ancient texts, you probably want to understand what they say. This holds true even if you take a spoken-language pedagogical approach. Reading Greek is the point of all learning of Ancient Greek. Period. If you are passionate about communicating in Greek concerning the wide range of normal happenings in an average day, then learn ελληνικά (that is, Greek as it is spoken today) and go talk with the approx. 14 million Greek speakers in the world today. We are on this journey of Greek learning because we want to be able to read texts written a long time ago in κοινή (or Classical, Homeric, Byzantine, etc.).
That gives us a clear goal to work towards: knowing enough vocabulary to read your desired Greek texts with comprehension (in a later post I will address some of the advantages, from the point of view of learning vocabulary, of working with a fixed corpus of texts). To get a handle on this goal we need to back up and think about what reading is and the role of vocab in reading. To wrap our minds around the task and give clear focus to our goals we need to grasp two very important numbers: 90% and 98%.
Reading is magic
Before the numbers, lets just ponder for one brief moment the magical thing that is reading. It has become so habitual for us, likely decades ago, that we can no longer not read words in front of us in a language we know. And that last point in key: in a language we know. As soon as we try to “read” in a language that we don’t know, or one we don’t know very well, we quickly (re)discover how incredibly difficult and frustrating reading actually is.
So what is going on between our ears when we read? Take a quick look at this definition of reading from a reading researcher:
Reading can simply be defined as a complex ability to extract, or build, meaning from a text. However, this definition, by itself, is not very informative. The most commonly accepted way for researchers to explain the above definition is to identify the key component abilities and skills that allow reading comprehension to emerge. Reading comprehension involves abilities to recognize words rapidly and efficiently, develop and use a very large recognition vocabulary, process sentences in order to build comprehension, engage a range of strategic processes and underlying cognitive skills (e.g., setting goals, changing goals flexibly, monitoring comprehension), interpret meaning and evaluate texts in line with reader goals and purposes, and process texts fluently over an extended period of time. These processes and knowledge resources allow the reader to generate text comprehension to the level required.William Grabe, “Key Issues in L2 Reading Development,” 8.
That definition almost leaves you breathless. What hopefully becomes clear is that reading is a really complicated set of brain gymnastics and when we are trying to read in an L2 (that is, a second language, meaning any language besides our mother tongue), we are thrown right back into the immense difficulties of reading. And not having a “large recognition vocabulary” is certainly a huge one of those difficulties. But how many words do you actually need to know to read a text?
90% and 98%: the magic numbers from reading research
It turns out, it is usually more helpful to consider not a raw number of words (though this can be calculated in a corpus language like Anciet Greek), but to think in terms of the percentage of words on any given page that you know. Research in reading in general and L2 reading specifically has come up with two important numbers: 90% and 98%. These conveniently describe two reading experiences: fluent reading and “frustration level” reading.
90% = Frustration = “I can’t read this!”
If you try to read a page of Greek text and you know less than 90% of the words on it you are reading what reading researchers call a frustration level text. The name is pretty self-explanatory. Reading a text like this is frustrating, because you can’t understand it, so you give up.
Let’s think about that in practical terms. 90% vocab coverage means you don’t recognize 1 word out of every 10 you see, or basically one word out of every average line of text in a printed Greek text (at least this holds for various Greek New Testaments I have looked at). What does that actually look like in a real text? Lets look at John 6.7 for an example (its 15 words long):
ἀπεκρίθη αὐτῷ ὁ Φίλιππος· διακοσίων δηναρίων ἄρτοι οὐκ ἀρκοῦσιν αὐτοῖς ἵνα ἕκαστος βραχύ τι λάβῃ.
Philip answered him: “200 denarii worth of bread would not suffice for this crowd such that each would receive some.”John 6.7
I have highlighted just one word that a reader likely would not know. Without this one word the sentence is largely obscure in meaning. At 90% vocabulary coverage this verse is frustrating, but not too bad. Just imagine, though, a whole page where you couldn’t really understand any sentence because each one was missing a key component. That’s frustrating. And the lack of understanding from the previous sentence snowballs into an even greater lack of understanding for the next sentence, ad infinitum. That is, in brief, why you need to know a lot of vocabulary.
98% = fluency level = “I can understand this”
The land of happy reading, by contrast, starts at around 98% vocab recognition. That means that out of every 100 words (roughly 10 lines of text) you only don’t know 1-2 words. This is usually manageable to read in fluent reading. To sum it up, reading a text with comprehension and fluency requires that you know essentially every word on a page before you sit down to read it.
There is a happy medium level: 95%. At this level a text is considered an appropriate instructional text. “Instructional text” is something like a book you have used in a classroom where words you are supposed to be learning are glossed for you. When you know almost all the words on a page, you can successfully read a text with a little bit of help. But dip just a few words/page below this 95% level and suddenly a text is too cluttered with unknowns to be understandable.
Vocab = Necessary for Reading Comprehension
What is the upshot of these numbers? If your goal is to read Greek, any sort of Greek, you actually have to know words; a lot of words. There is no shortcut around this. Trying to read is really frustrating when you don’t know the words you are looking at. And nobody likes doing things that are really frustrating.
So what do we do about that? How do we learn words so that we can read? In the next post I will begin to answer this question by discussing some of the research about learning L2 vocabulary, especially some of the surprising findings about the link between knowing how to say words and knowing what they mean.
 These numbers were developed with reference to English, primarily. For the sake of the argument, I am assuming they are a reasonable proxy for the experience reading Ancient Greek as well. On these numbers, see I.S.P. Nation, Learning Vocabulary in Another Language, 2nd ed. (Cambridge: Cambridge University Press, 2012), 144–47, and William Grabe, Reading in a Second Language: Moving From Theory to Practice, (Cambridge: Cambridge University Press), 270-71.
 William Grabe, Reading in a Second Language: Moving From Theory To Practice, The Cambridge Applied Linguistics Series (Cambridge: Cambridge University Press, n.d.), 271.