Pile the bodies high at Austerlitz and Waterloo. Shovel them under and let me work—
I am the grass; I cover all.

And pile them high at Gettysburg
And pile them high at Ypres and Verdun.
Shovel them under and let me work.
Two years, ten years, and passengers ask the conductor:
What place is this?
Where are we now?

I am the grass.
Let me work.

How does the use of repetition best contribute to the meaning of the poem