Stanza one begins with a command: "Do not go gentle into that good night." This first line can also be interpreted as an entreaty, with the speaker not just commanding but begging the reader not to go "gentle" into death, meaning not to give up without a fight. In this context, "night" is a metaphor for death, making "day" and "light" metaphors for life. Thomas expands on this metaphor in the second line, where the speaker proclaims that the elderly ("old age") should fight ("burn and rave") against death ("close of day") just as fiercely as if they were still young. Stanza one ends with the speaker's second command: "Rage, rage against the dying of the light." This deepens the metaphor of light as life and suggests that though the dying of the light (like the setting of the sun) is a perfectly natural phenomenon, people should still fight it. Everyone dies, the speaker knows, but that doesn't mean you have to go quietly. Thomas emphasizes this point by repeating these two commands throughout the poem.
In stanza two, the speaker introduces the first of four different kinds of men: wise men. These wise men, like the speaker, understand that death is inevitable ("know dark is right"), but this intellectual conception of death can't change their nature ("their words had forked no lightning"), so even these wise men who know death is coming fight against it in the end.
In stanza three, the speaker introduces a second group of men: the good men. These men are shown in their "last wave" (where "wave" means both the last stage of their life and the farewell wave they give to the ones they leave behind). "Crying" also has a double meaning, referring both to the act of crying out or shouting and to crying or weeping. These moral, upstanding men are upset because the good works ("frail deeds") they did in life were cut short, because...
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