Read "Mors" at The Eldritch Dark:
Clark Ashton Smith (CAS) presented this poem as being translated from the original French of Christophe des Laurières, but according to Donald Sidney-Fryer*, des Laurières was simply a pseudonym for CAS himself. So I'll proceed on the assumption that this poem is exclusively the work of CAS!
And it's quite a morbid little affair, yet rich with the melodious voicing that is present in CAS' very best work. Phrases such as "moonlight on the marble sea" and "The bitter splendors of the sun" are practically short poems by themselves, and woven into the sixteen lines of "Mors" they cast a hypnotic spell that lasts all the way until the exquisite closing stanza:
They pass. . . . The secret peace I crave
Like a black shroud enwraps me round—
Lost, and voluptuously drowned
In the dark languor of the grave.
This is one of those poems from CAS that really just cannot be improved - the use of iambic tetrameter is regular, musical, and morbid, all in perfect proportion.
*See the "Pseudonyms" section of Sidney-Fryer's Emperor of Dreams: A Clark Ashton Smith Bibliography published in 1978 by Donald M. Grant.