Origin of ~なければ ならない?

Question

The expression ~なければ ならない if I learned correctly means "must not not do ..." as in: 日本語を勉強しなければなりません。 You must not not learn Japanese. (i.e. you need to learn Japanese) However, taken on face value it doesn't really make sense. しなければなりません translates into "if (you) don't do, doesn't become (what?)". The confusing part is that a direct translation into *modern colloquial* Chinese makes sense: 你不学日语的话，不成 = "If you don't learn Japanese, not become" = "You must learn Japanese". This seems like a Japanese borrowing from a common Chinese phrase; 不...的话 acts like ～なければ, and of course なる is sometimes written 成る. However, the expression does not exist in Classical Chinese, which I presume Japanese borrowed the most (including all the un-Mandarin-y readings). Classical Chinese would use 不可～. I'm suspecting this might be a Chinese loan from Japanese, just like how 不不不不 is a syntactical English loan of "no no no no" and not really parseable (Chinese has no word for "no", only 不 = not = ～ない). Putting something like "must not" in a verb at the end is very un-Chinesey. Modern Mandarin-based Standard Chinese has also borrowed lots of 和製漢語 such as 民主, 共和国, 歌姫, 写真, カラオケ, and pretty much all the vocabulary related to biology and political science, curiously. So when did this expression start in Japanese? Does any equivalent to ~なければ ならない exist in, say, Classical Japanese or Old Japanese? If so, it'd probably be the Chinese borrowing from Japanese, not the other way around.

Answer 1

In Classical Japanese, there is a copula "NARI," which became "NARU." The -BA construction is perfective, so it takes for granted that something has happened and complete.

Paired with something in the mizenkei (imperfective form) it forms a hypothetical if-when statement, it states that if-when X happens, Y will be the possible result.

The overall translation would be "if not ~, will not be." In English, we have a similar phrase in "it/that won't do."

In other modern phrases which express obligation are a bit more direct, ～ないとだめ, for example. Literally it would be "if/when not ~, is bad."