A limited palette

The repetitive language echoes the idea of being on a road, constantly travelling. 

 'nights dark beyond darkness and the days more gray each one than what had gone before.'
 'From day dreams on the road there was no waking'
'ashen'
'Darkness'
'night'

There is a powerfully poetic effect in the simplicity of the language. By avoiding rhetorical flourishes and elaborate language the writer makes a stronger impact.  

'Like pilgrims in a fable swallowed up and lost among the inward parts of some granitic beast."

'If only mt heart were stone'. 
'There is no God and we are his prophets.' 

Avoiding emotional language and keeping it simple makes the narrative all the more emotionally engaging. 

'She was gone and the coldness of it was her final gift'.
 'Maps and mazes. of a thing that cant be out back. Not to be made right again.'
 'Okay. Okay.'