Move him into the sun—
Gently its touch awoke him once,
At home, whispering of fields unsown.
Always it woke him, even in France,
Until this morning and this snow.
If anything might rouse him now
The kind old sun will know.
Think how it wakes the seeds—
Woke, once, the clays of a cold star.
Are limbs so dear-achieved, are sides
Full-nerved,—still warm,—too hard to stir?
Was it for this the clay grew tall?
The narrator considers how powerful the sun is – it allows seeds to grow into plants, and at the time of the formation of the planets enabled the Earth (the “cold star”) to host life. Therefore, in desperation, he appeals for the sun to revive the soldier. 
 
 The ‘cold star’ is an  oxymoron . The once lifeless planet acquired life — but the once living young man has turned cold in death. There may be a reference here to  Darwin’s theory of Evolution , which explains the nature of life and how it evolved. It seems that Evolution has reversed, and Man, in his sophistication, has turned life back to coldness and death. 
 The rhythm in the second stanza, unlike the first, is jerky and halting. Note the  caesura  after ‘seeds’, where the line is cut short to indicate the pause for deep, troubling thought.