Dylan Thomas's title itself is metaphoric for his plea to his dying father; in this title and refrain, Thomas urges his father to affirm life until the very last breath: "Do Not Go Gentle into the Night."
In the first stanza, Thomas uses the images of fire and light also as metaphors for passion as he writes metaphorically that "old age" should burn and rave "at the close of day," a metaphor for an intense resistance to the end of life.
In the second stanza, death is difficult for "wise men," the intellectuals who accept it, but their work is not finished, so they do not wish to die. Their "lightning" is the image for their works that light up minds:
Because their words had forked no lightning they...
The third stanza contains the metaphor of "good men," men who have lived sensible lives, "the last wave" ; that is, the last sensible men who are the final ones to face death, and, in so doing, they also wave goodbye. They are "crying how bright/Their frail deed might have danced." The image of crying is the sound of bemoaning as well as their calling out to be the last to face death.
Contrasted to the sensible men are the "Wild men" in the fourth stanza who "caught and sang the sun in flight." This image is powerful and ebullient compared to the frail deeds of others. But, these men, too, albeit filled with passion, will succumb to death.
In the fifth stanza, the image of "grave" is also dual, as it means "serious" as well as the shoveled earth for the coffin. Yet, although they may be blind, they can perceive more than others and "blaze like meteors," an image most bright.While the refrain underscores the passion suggested in the previous stanza there are contrasting images here: light/dark, blind/sight, and grave/gay.
In the final stanza, the image of "fierce tears" suggests the inevitability of death (tears), until their resistance to death up to the very end (fierce).