I sense subtle, even subliminal themes, in this poem.
There's an element of conquest, isn't there, Jeremy?
As they contest their fate, they strive to take over a place that doesn't belong to them. It's as if their interstellar crusade is foiled by an almost poetic intervention by the cosmos ... a cosmic 'Quill Fire,' so to speak, saying, "Thou shalt go no further. You have taken too much already."
Disclaimer: I'm not a lunatic. There's more going in this poem than first meets the eye. And we all need to be concerned. :-)
Every reader can see what he pleases, although, I had not planned a cosmic intervention. I wanted more to emphasise how humans repeat in the same cycle of behaviour.