Heimhenge just posted on "the calculus" and it reminded me of a question I used to have when taking French: Â Why do they speak of "La France" and "Le Canada"? Â If they did it all the time I'd just shrug and learn to do it, but no, it's only for some countries, and there's no discernible pattern so I just have to memorize them. Â Who thought that up?
It finally occurred to me that we do it in English too; the problem is only that we do it with different countries. Â We say "Canada" and "France", but "the Hague", "the Netherlands" and "the Vatican". Â I can see a justification for "the Netherlands", and of course for terms like "the Soviet Union" and "the United States", but not so much for "the Congo". Â I guess there's nothing for it but to stop complaining and learn it.
We should prohibit using definite articles in place names with the United States, from Bronx to Angeles to Paso to Moines.
On a related topic, has anyone here heard of the Atlas of True Names? Seems some clever British publisher decided to put out maps that translate all the place names into English, so that Canada becomes "Land of Villages" and Mexico "Navel of the Moon". I've often thought that the occasional attempt to make English the sole official language in Arizona should be answered with a list of names that would have to change: "Nogales" to "Walnuts", "Tucson" to "Black Foothill", and "Eloy" to "OMG!"
Ahhh ... but then, since we changed Squaw Peak to Piestewa Peak, what would we change that to next? Â 
Getting to Bob's comment, I think it's hard to avoid the definite article when the country name is collective (United States, United Arab Emirates, Soviet Union, Netherlands, etc.) The Democratic Republic of the Congo is a puzzler.
But what you say about exceptions is a good point. I have no problem believing The Vatican is an example of that same affectation I hypothesized about calculus in another thread.
Clueless about The Hague though. Likewise The Bronx.
RobertB said: so 'The' is thrown in to instruct the ignorant plebeians what a significant concept it was, or just to magnify it to make oneself sound important.
And that's what my original point was regarding "the calculus." I know a lot of people who have taken calculus [Rant: I refuse to predicate calculus with "the"] and feel quite smug about their accomplishment. But calculus is routinely taught in high school these days, so how hard can it be? Granted, some of the calculus courses one can take in college are truly difficult to master, and success in those courses is a real reason for pride.
Still, I've never heard "the arithmetic" "the algebra" "the geometry" or "the trigonometry."
Ngrams shows use of "the calculus" peaking around 1950 and declining since. That's around the time of the Space Race between the US and USSR, when all STEM subjects were heavily promoted in schools. So perhaps that usage was an appeal and/or teaser to join the "elite" corps of scientists who understand calculus?