Themes of isolation, loneliness, and death characterize this eight-line poem. The wind moans in grief beyond words; the storm rains in vain; the trees are bare and straining under their own weight. The world is all caves and gloom, all wrong!
A dirge is a song that is sung at a funeral. The speaker piles one image of nature upon another to describe the grief he feels, including the moaning and wild wind, the sullen clouds, the sad storm, the bare woods, the deep caves, and the dreary main. Note that the speaker is anthropomorphizing his surroundings to express his grief, and almost all of the nouns are anthropomorphized via sad and gloomy adjectives. Put all together, the poet expresses the frustration of feeling that the whole world is “wrong” and is grieving its own sorry state.
It is normally assumed that in this poem Shelley is mourning both the death of Keats and the death of his son William, who was buried in the same place in Rome as Keats. The untimely death of Keats reopened the floodgates of emotion for Shelley, inevitably leading him to revisit the sadness and pain he felt for the death of his infant boy.
The rhyme scheme of these eight lines is abab cccd. The triplet of vain/strain/main in the second half of the poem adds to the sense of the piling up of emotions. It also has the effect of slowing down the poem.
The second line, “Grief too sad for song,” is a common poetic trick—stating that the emotion is so strong that it cannot be put into words. Here, the emotion is grief, an uncommon emotion in Shelley’s poems, despite the sadness he often felt in life. In his more “political” poems, Shelley has answers: rise up against the oppressor, turn to reason, appreciate life for what it is. Here, nature itself is profoundly disturbed and is no solace. Indeed, the whole world is “wrong.”
The last line, “Wail, for the world’s wrong!” is thus the one source of hope, despite everything. The world itself has not been wrong before; nature has always been greater than man and beyond understanding, yet approachable enough to understand. Here, nature is grieving with him, so if the world is wrong, so is he, and the answer seems to be that eventually, both nature and the poet need to stop moaning and mourning. If he knows what is wrong, he must also know that there is something somewhere that is right, and we know from Shelley’s other poems that he has a lot of ideas about how to seek out what is right and good.