I have always been interested in the negative polite (〜ません) and negative past-polite (〜ませんでした) inflections of verbs.
My understanding is that ます is an inflectable function word (助動詞), so I'm wondering why the negative form ends with ん. Is that a contraction of ぬ perhaps? (Also why is the 未然形 ませ rather than something more regular, like まさ?)
The really weird thing for me is でした (the past inflection of the polite copula), showing up for the negative past-polite form. Has this always been the way to handle this sort of semantics, even in Classical Japanese, or is this a recent introduction to the language?
Although I think there is probably no really satisfying answer to why things are like this, I do think it'd be interesting to know how things evolved through time, so any answers revealing some of that information are welcome!