The grammars say that misereor takes the genitive to express its object. So where does miserere nobis in the Latin Mass come from? Is it just a later (post-classical) development where the dative(?) is used, or is there another explanation?
And now please excuse the cross-posting from the M&F forum, but the question there seems to have fallen under the radar, or it wasn't sufficiently clear (or no-one knows the answer....).
From the way M&F introduced quot? (how many?) and quantus -a -um? (how much?) it looked as if you would use the former for discrete items that could be counted (togas, slaves, days) and the latter for continuously varying things that would be measured (how much wine left in my cup, the size of my country estate). However, M&F use quantus with days (Quantīs diēbus post mē Rōmam proficīscī vīs?) in one of their own translations. Have I read too much into this, and there is little difference? Or is it a general, but not hard-and-fast, rule?