Written as a thank-you note to the ground itself, the poem starts out tender and gradually grows uneasy. The speaker is grateful for something we usually take for granted: that the earth is simply there, solid under our feet. A dream of endless falling shows how frightening it would be if it weren't.
The thanks then turn darker. The "enormous reserves of darkness" seem to point to fossil fuels, which we burn to push back the dark, and the phrase "ashes to ashes" ties that burning to death and burial. The politeness of the letter makes the irony sharper, because we are thanking the ground while using it up.
The final lines, "letting us all fall down," echo a children's rhyme but also mean dying, and the ground receives everyone in the end. The mood is quiet, gentle and a little wry, with grief and a sense of guilt underneath. The short lines on the page even look like leaves drifting downward.