Read "The Song of A Comet" at The Eldritch Dark:
Clark Ashton Smith (CAS) included this poem in his first published collection, The Star-Trader and Other Poems (1912) where it ran to 60 lines of verse. When it was later collected in his Selected Poems (1971), it was significantly edited and expanded to 71 lines.
Since CAS included the longer version in his career-spanning Selected Poems, I'm assuming it is the author's preferred version. That same longer version is available via The Eldritch Dark, so that's what I'm considering in this blog post.
This long poem presents quite a journey, as a comet follows a unique path all its own through the cosmos. Some of the visions that the comet encounters along the way are quite thrilling:
Upon the shadowy heavens half-revealed,
I show their planets turned,
Whose strange ephemerae,
On adamantine tablets deeply written,
In cities long unlitten,
Have left their history
And lore beyond redemption or surmise.
CAS emphasizes that the comet follows a route that it does not choose, and nor does it have any notion of where that route will take it in the future. I don't believe any sort of metaphor is intended by the author, but it is appealing to imagine the comet experiencing an endless series of incredible visions as it wends its way through the limitless universe.