The overarching theme of the poem is that the human race is not terribly important in the grand scheme of things: if it completely disappeared, nature would go on, indifferent to the change. Since the poem is subtitled "War Time," the implication is that we humans could destroy ourselves through warfare. We, therefore, need to take care of ourselves and ensure our own survival. Nature will not protect us or care if we go extinct.
The poem is a series of six couplets, each of which comprise a two-line stanza. The couplets need to be taken as a whole.
In the first couplet, the speaker uses scent, sight, and sound imagery to describe a beautiful natural world of swallows, soft rains, and the scent of the earth, showing how lovely nature is.
In the second couplet, the speaker continues to describe nature's bounty, such as the sound of the frogs and the beauty of the blossoming plum tree.
In the third couplet, birds sing, perching on the wire fences humans have erected.
Having established nature as...
(The entire section contains 3 answers and 1029 words.)