This early sonnet by Clark Ashton Smith (CAS) was unpublished in his lifetime, and not available on The Eldritch Dark, so I'll start with the text of the poem itself:
O riddle of the years, that is this desert place
O'er Egypt's desolation guard doth keep--
Here where her shattered glories buried sleep,--
Upon thy sealèd lips and mocking face
Which holds the secrets grim of Time and Space,
We look, and question thee. Before thee creep
How many, and from out their darkness deep
Crave light and knowledge! Ne'er in any case
Dost thou an answer make, for on thine eyes
And lips hath Silence laid her awful seal,--
Her order and her spell inviolate.
But oh! If thou should speak, who art all wise
Heeding at last our myriad-voiced appeal,
What might we learn, of life, and death, and fate!
This seems like a relatively minor item in CAS' poetic oeuvre, technically faultless but lacking in any very original ideas.