In Dylan Thomas' "Do Not Go Gentle Into That Good Night," the speaker is a son talking to his aging father and pleading with him to fight against death. The son knows that death is the inevitable end to every life, but feels one should not give up to death too easily. By using metaphor, imagery, and repetition, Thomas reinforces the son's message that aging men see their lives with sudden clarity and realize how they might have lived happier, more productive lives. These men rail against fate, fighting for more time to set things right.
The son uses dark and the end of day as metaphors for death. He tells his father "old age should burn and rave" at death rather than grow dim and peacefully slip away. The light and dark comparison is also used to create a vivid picture of dying men struggling to keep the darkness at bay. "The dying of the light" brings a sudden, brief illumination to old men so that they see their lives clearly when it is too late.
The son tells his father how wise and good men have spent their lives and that they do not give up easily. Wise men know that death is appropriate, but they do not embrace it. These wise men fight death because they feel their words have not been adequate enough to touch or illuminate others. The son creates a visual image of the inadequacy wise men feel upon realizing their words have not enlightened others--"their words had forked no lightning." The son also mentions good men who do not die peacefully. These men despair that their feeble deeds did not accomplish enough. Even though they were good men, they feel they could have done so much more if given the time.
The son next tells his father how wild and grave men also struggled with death. Wild men spent their lives frivolously, wishing time on its way. They learn when it is too late that they hurried time too fast and now they cannot recapture what they so wantonly spent. Their lives were foolishly wasted. The son also mentions grave or serious men who review their lives with a swift lucidity when death is upon them. These solemn, sober men now realize life could have been more joyous had they been a little more "blind." If life is taken a little less seriously, one "could blaze like meteors and be gay."
Repetition at the end of each stanza is effectively used to reinforce the message to fight back against death. The son implores his father to hang on any way he can and begs him to use joy or tears or anger to remain in this life. Other men, be they wise or frivolous, serious or sincere, have fought back at the end and so should he.
Through the use of imagery and metaphor, Dylan Thomas paints a vivid picture of a son pleading with his father to resist "the dying of the light." Without the repetition at the end of each stanza, the message would have been less strident. By mentioning other men and their regrets over failures, the son is telling his father it is not too late. If he will resist death, he might be able to change his life. When death comes, men learn what they might have done differently with their lives.