Actually, it's more like "The Natural World and Man." Sure, it's a small adjustment, but for "The Darkling Thrush," it's a key one. What with Frost and Winter and the land and birds stealing the show, there's not all that much space for, well, humans. It's not that humans don't exist. It's just that they're apparently not worth writing about. Life and death take on epic proportions in this poem, and only elements as ancient and enduring as Frost seem big enough to fill the poem. With all that bigness and grandeur, the tiny thrush seems completely and totally outmatched. Until, that is, he starts singing. Could Hardy be using this as a metaphor for people, as well? Hmm....
This poem depicts humanity as a life form on the verge of extinction.
Although "The Darkling Thrush" appears to be about the ending of the world, it's actually a celebration of new birth and new beginnings.