This is another sonnet unpublished in the lifetime of Clark Ashton Smith (CAS) and not available on The Eldritch Dark, so here's the poem itself:
Not as a sea of flame whose waves and deeps
Shall gulf the suns and worlds--but as a night,
A darkness and a silence past all light,
Beyond all sound, Oblivion waits and sleeps.
Within its absolute encircling sweeps
The universe--a stream of stars that sight
Deems countless, but upon whose gleaming flight
Like some eternal tide, Oblivion creeps.
A darkness and a silence! There shall draw
To one eclipse the systems and disperse
This strange and troubled dream of Time and Place.
Then, sun nor world shall be nor light nor law--
But endless night and emptiness of space--
A vast nirvana of the universe.
The personification of Oblivion is very interesting in this poem. With the phrases "Oblivion waits and sleeps" and "Oblivion creeps" we have distinct actions joined by a rhyme which makes Oblivion an active living force that animates the sestet.
CAS intriguingly ends this sonnet with the line "A vast nirvana of the universe." The word "nirvana" implies a release from the physical realm of life, with Oblivion acting as a catalyst for achieving that state. This anticipates Sigmund Freud's articulation of the "nirvana principle" in Beyond the Pleasure Principle, a book that wasn't published until 1920 (evidence suggests that CAS wrote "Sonnet on Oblivion" in either 1911 or 1912).