OK, while we wait for details let's get back to this.
Unlike dealing with translations, Longfellow spoke (and artistically used) the English language; when he said something he knew exactly what he was saying. In this poem, in the next line, he is "seeing" something that is coming from somewhere. In this case, "somewhere" could be a memory of a talk he had with his grandfather when he was a child, but it's impossible to say for sure. I'd rather a simple answer than a quantum leap to a projected communication from - some other source - like ET? Anyway, he says:
Like the astrologers of eld,
In that bright vision I beheld
Greater and deeper mysteries.
He was looking at a balance in the hands of time, which would another way of saying something like: You will eventually get yours.
In this picture he sees the sun setting, and on the eastern horizon he sees the scales of night (the constellation Libra, AKA the scales of Justice, later connected to Virgo) rising.
From this point he talks poetically about the Lyre.
Like the astrologers of eld,
In that bright vision I beheld
Greater and deeper mysteries.
I saw, with its celestial keys,
Its chords of air, its frets of fire,
The Samian's great Aeolian lyre,
Rising through all its sevenfold bars,
From earth unto the fixed stars.
And through the dewy atmosphere,
Not only could I see, but hear,
Its wondrous and harmonious strings,
In sweet vibration, sphere by sphere,
From Dian's circle light and near,
Onward to vaster and wider rings.
Where, chanting through his beard of snows,
Majestic, mournful, Saturn goes,
And down the sunless realms of space
Reverberates the thunder of his bass.
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I saw, with its celestial keys,
Its chords of air, its frets of fire,
The Samian's great Aeolian lyre,
The lyre was originally bestowed with the qualities to invoke and communicate the messages of the gods. In other words this isn't just a bunch of words, this is coming from – upstairs? Or, is he just remembering things he had heard from earlier in his life, and possibly a study he did? I don't know.
This was further explained to me by someone I know.
Aeolian is the 5th mode of the major scale, typically recognized as a ‘minor’ or sad sounding scale. You've heard this a lot in Blues stuff, however, Blues doesn't utilize all the same notes in the scale but doesn't go outside its bounds and you typically get the same mood.
"Rising through all its sevenfold bars." Seven notes in each scale, the 8th is the octave where it starts all over again but at a higher pitch.
So then, should we go as far as to say that we have a ‘sad’ message from ‘above’ about something ‘cyclical’ (octave coming) tied to ‘judgment?’
All I know is that he continues by saying:
Beneath the sky's triumphal arch
This music sounded like a march,
And with its chorus seemed to be
Preluding some great tragedy.
Marching music has military roots. What exactly are we looking at here that is “preluding some great tragedy?”
Let's leave it here for now.