Jack --

I don't really think that

Her cheeks were rosy,
her tears were dew

is a complex metaphor, but rather, an extended one: Taking one image (of a rose in a garden) and layering as many details over it as possible, making that one metaphor stronger. Just as roses are wet with dew, her cheeks were wet with tears, therefore, her cheeks were like roses in more ways than just their color -- and you could extend that metaphor even further by saying something like her first blush of love was a rose bud opening, and after she is heartbroken, and her cheeks lose their color, the rose that faded and dropped from the vine (why do we always hear about the rose on the vine in song, but not rose on the bush? ;-)).

What I'm talking about is layering different images together in a song -- things that don't ordinarily fit together (the way roses and dew do) -- a bit like the five blind wisemen describing an elephant: It's a rope, a tree, a fan, a snake, and a wall.

Like elephants, some ideas are too big to fit a single metaphor. But can those ideas be put into a song, where language is kept to its bare bone minimum (Songs must say things even more succinctly than poems), without thouroughly confusing the listener?

Are there some ideas that just cannot be sung about?