This is another poem unpublished in the lifetime of Clark Ashton Smith (CAS), and also unavailable on The Eldritch Dark, so I'll begin with the text itself:
From dreams of light and sound one felt his soul
Borne out to some extremity of night
In voidness where the universe is thin.
Aghast and pale above the gulfs, the stars
Watched as he felt tremendous glooms
Until they shrank and drew [ ] back
From gulfs past any star's Titanic sight.
Despite being incomplete (note the blank space in line six) and quite short, this early poem by Clark Ashton Smith is quite effective at painting a portrait of an epic dream of cosmic dislocation. The first three lines are especially compelling, ending with the succinct phrase "voidness where the universe is thin", a handful of words that express an immense idea.