Read "The Chimera" at The Eldritch Dark:
This is a powerful sonnet from Clark Ashton Smith (CAS). On reading it I am immediately reminded of one of my favorite lines from CAS' outstanding long poem "Nero". The line from that earlier poem reads: "Destruction crouching at the back of Time", which provides an interesting echo on how the subject of Time is handled in "The Chimera", particularly in the wonderful final stanza:
He crouches like a passive sphinx before
Some temple-gate, or grinning, moves to grant
Thine entrance at the monarch's golden door.
In this poem, CAS has captured the notion of Time as a vector of inevitable destruction, and the characterization of Time as "a passive sphinx" that is "grinning" serves to drive the knife in further with a tone of mocking finality. If CAS is a jester in the court of human vanity, this sonnet could well be his ultimate quip.