Thanks, this is really interesting! By the way, I don't think "when that April, with his showers sweet" is grammatical modern English -- it should probably be

Thanks, this is really interesting! By the way, I don't think "when that April, with his showers sweet" is grammatical modern English -- it should probably be "when April, with its showers sweet" (and even that is unusual poetic syntax: in normal language you'd say "sweet showers").