I'm currently attending a German B1 course and I've been listening to some "deutsche Volkslieder" by Brahms, and I'm noticing a lot of unusual syntax. For instance in the song "Es war ein Markgraf überm Rhein", in the last stanza there's the line "Ich will kein Weck, ich will kein Wein." Shouldn't it be "keinen" in both cases since both are masculine? In the song "Es ritt ein Ritter." the final line reads "mein jungfrisch Herze muss sinken", shouldn't it be "jungfrisches", also why is it "Herze" in stead of "Herz"?
I've also noticed word order being changed in ways that, from my admittedly sparse knowledge, the grammar shouldn't allow. In "Soll sich der Mond nicht heller scheinen" there's the line "So will ich diese Nacht gehn freien", again, shouldn't it be "So will ich diese Nacht freien gehn"?
I'm encountering a lot of examples of the grammar--for lack of a better word--ignoring its own rules, adjectives not declining, wrong verb order, etc. It seems that poetry allows for much more fluid construction, and I was wondering if this behavior had a name, or if there were limits to it?