Don't expect much more from me.
I think I'll just splurge everything I know here, then I won't need to contribute further.
I only ever learn a language in order to read its literature. I haven't left England for about 12 years. I can speed-read Proust, but I can only speak a little French, and Spanish. They talk about "menu French" as being basic French, but ironically I find whenever I order from a French menu, what the waiter brings is mostly a surprise! My second language is German to my regret, and I almost never read it. I haven't got the energy to travel on the kind of money I've got. I haven't had a passport for 11 years. After about 15 years of learning a language I feel that I'm not going to improve rapidly any more, so I switch to another language. For the last 18 years I have read nothing but Greek and Latin in parallel. I read a little general linguistics in the 80s and decided it was of no interest to me, so anyone who wants to quote Chomsky, I'll just go, mneugh. I wonder if Chomsky is like all those anthropologists out there - learn 50 words and pretend you know a language?
I am a slow learner. Others can quite easily accomplish in 3 years what takes me 15 years. I "learn" 10,000 words of vocab per year. But I calculate that each rolling year I forget 80 to 90% of everything I "learn".
I think the problem with portraying French as a "limited language" is that it is not limited compared with the percentage of it that any one person can and will use. (Another thing about Le Petit Robert, btw, is that under every word it lists all its homophones, which is fun). I've never read English formally, so don't expect me to know much about the history of the language. In fact, I've read so much other than English, that I've never had the time to read much English.
Languages, rather than gradually absorb from other languages, seem to me to go through periods of formal rearrangement and mass adoption. In England we had the 12th century renaissance, which my German Classics professor had never heard of. German (in addition to a biggie in the 9th century - the amount of Latin in German is very high. In fact the West and the East Germanic languages went through great changes then, even in their grammar - West Germanic employed Jerome's Latin New Testament to restructure their grammar, and East germanic - Gothic - employed the Greek New Testament to restructure their grammar!) went through one of these in the 18th century for some reason. I suppose it was the Enlightenment - the old words for uncle and aunt went out (Oheim, Muhme. Eme is an archaic English word from Oheim. I don't know what the female equivalent is) and the French ones came in (Onkel, Tante), among a lot of other stuff you'll have to ask a German specialist about.
When Chaucer was alive, the Renaissance (originally, technically, intended as a rebirth of ancient Roman culture) led to a boom in vernacular Italian writing that Chaucer picked up on. That's all I know. Shakespeare caught the tail end of that. I guess there was a big formal development between the two.
It is said that there was a retrenchment of German in the Nazi era, but others say that's a myth. The other thing is, even if English has a lot of synonyms, it's not necessarily true that they are all in current use at the same time. Crossword compilers don't distinguish between old and new usages - it's part of the fun. Most of our words were originally Latin. Possibly someone in the Englightenment suggested Greek equivalents for educated use?
Nietzsche wrote something about Mitleid being a bad thing. Mitleid means sympathy. Sympathy and compassion are synonyms. Sympathy is Greek, compassion is Latin. So, are sympathy and compassion bad things? Thing is, our compound words are opaque. German compound words are transparent. Mit ('with'), Leid ('suffering' - passio is Latin, pathos is Greek for any experience, but often suffering, especially in later Christian usage). I suspect the main thing to take from Nietzsche is the word-play, which is untranslateable. You can help others in their suffering, but would you suffer with them? What would be the sense in that? As I say, I don't read German, and I've never had time for more than Zarathustra, unfortunately.
Frankly, if you ask me what the Enlightenment was, I forgot 30 years ago and I'd have to Google it. Sorry, a dozen bad nights in a row, so I'm not trying to be very helpful right now! I'm also aware that I lecture people too much. Dammit. Partly this post is to save me responding "I don't know" to any specific questions such as Jeffrey's! (I haven't got around to reading Les Symbolistes, for example. When I abandoned French, it was with a lot of stuff unread)
1975 Calatayud y Gisbert, Yamaha CG131S.