Read "The Saturnienne" at The Eldritch Dark:
This poem from Clark Ashton Smith (CAS) was published in Weird Tales magazine in 1927. Prior to that, in 1925, CAS sent a draft of the poem to his mentor George Sterling, who commented*:
This "Saturnienne" is in your best vein. As often, I had to consult the dictionary, and am by so much the wiser. I recall Bierce writing somewhere in praise of archaic words, commenting on their poetic value.
There is no doubt that "The Saturnienne" is a showpiece for CAS' extensive English vocabulary, but in the service of the exotic scenario, the vocabulary is highly effective:
Amid her agate courts,
Like to a demon ichor, towering proud and tall,
A scarlet fountain spurts,
To fall upon parterres of dwale and deathly hebenon.
If a reader makes the effort to look up words such as "dwale" and "hebenon", those lines have a startlingly potent impact that would not have been possible with a mundane diction.
*See letter #346 in The Shadow of the Unattained: The Letters of George Sterling and Clark Ashton Smith published by Hippocampus Press.