What does dust symbolize in this novel?

 I just finished reading this novel and the last two paragraphs are DEEP with meaning.

Among many things that were repeated, I noticed dust was being repeated and it was definitely a motif.

So, I was wondering what it meant/ symbolized.

Check out this very last paragraph of this novel paying attention to dust...

"The desert he rode was red and red the dust he raised, the small dust that  powdered the legs of the horse he rode, the horse he led. In the evening a wind  came up amd reddened all the sky before him. There were few cattle in that country  because it was barren country indeed yet he came at evening upon a solitary bull  rolling in the dust against the bloodred sunset like an animal in sacrificial torment.  The bloodred dust blew down out of the sun. He touched the horse with his heels  and rode on. He rode with the sun coppering his face and the red wind blowing out  of the west across the evening land and the small desert birds flew chittering among  the dry bracken and horse and rider and horse passed on and their long shadows  passed in tandem like the shadow of a single being. Passed and paled into the  darkening land, the world to come."