I came across this article recently, which states: "Ever wonder why some languages are harder for adults to learn than others? The researchers point out that languages contain what linguists call a “kernel lexicon,” meaning a list of words that constitute 75 percent of the written language. If you know those words, you can make out much of the literature. These also are the words least likely to change even as the language morphs. The kernel lexicon for English is less than 2,400 words. If you know them you can read 75 percent of the text. The kernel lexicon for Russian is about 24,000 words. So, even though the whole of the English language has about 600,000 words and Russian has considerably less than half of that, without the crucial 21,000 kernel words, most Russian writing would be largely incomprehensible." Thoughts?