The latest Stack Exchange blog post contains the following section header:
In which we stop being dumb
I have never really understood what is going on in these "in which..." constructions at a grammatical level. Is it just an elision of something like "this is a section in which..."? Or, perhaps, is it an imitation of a famous quotation/title/etc. that has the same structure?
I feel like I've only seen this construction on the internet, which suggests to me that it is either a piece of internet lingo that I've somehow missed or a very new construction that hasn't caught up to me yet. I am a native speaker of American English, but am relatively ignorant of other varieties, so perhaps this is just a feature of BrE that I'm unaware of or something.
Note that I am not asking about constructions like:
In which of these two fields should I write my name?
These constructions are full sentences in which the preposition "in" has been hoisted to the beginning of the sentence, and I understand them perfectly well.