verbi inferni: quin
Here beginneth a series on Latin words which, for whatever reason, don't seem to stick well to my brain, in hopes that by ratting them out, they will finally choose to linger.

QUIN. Quin is just from "qui ne", which are both common enough words, except that it is apparently from some weird ablative form of "quī". So it's a question word followed by "lest". Anyway it is basically something you stick in the beginning of a phrase to show that you're asking a rhetorical question, along the lines of "why not". "Quin conscendimus equos?" Why not mount our horses? Why not indeed. It's just that the meaning apparently expanded from there, so it takes in senses like "without [doing something]": "Curiosus nemo est quin sit malevolus" -- No one is inquisitive without being eeeeeeevil. Or it can mean something like "but that not", or perhaps just "verily". Or "nay!" Though Latin already has a perfectly fine word for that kind of "nay!" -- "immo".

So, yes, a rhetorical gesture that kind of gets translated into a dozen different and obscure things in English. Meh.