What is the moral of the poem?

Although death permeates every stanza of the poem like a shadow hovering over the poet and his father, “Do Not Go Gentle into That Good Night” concerns life and how it should be lived. Dylan Thomas as the poem’s voice argues that those who have reached old age should not willingly consent to dying; he does not, however, denigrate death itself. Death is a “good night,” he writes, and extending the metaphor, he observes that “wise men” understand that “dark is right.” In the context of the poem, death at the conclusion of a long life is “good” and “right” because it is natural; death is not an aberration in the natural cycle of life but is instead the culmination of it. Why then should those who are old “burn and rave at close of day”? Why do the old men in the poem, those who are “wise,” “good,” “wild,” and “grave,” resist dying—and should resist, as he contends? The answer lies in how they have lived and in the regret they experience as their lives draw to a close.
Throughout the poem, being alive is associated with passion—with feeling deep emotion. It is also associated with using one’s gifts fully in the pursuit of something fine and truly remarkable. Thomas’s “wise men” and “good men” resist dying because they have not achieved what they could have achieved during their lives. His “wild men” had lived passionately as they “caught and sang the sun,” but they had failed to savor being alive, realizing “too late” their own mortality. The “grave men” resist dying because they understand with “blinding” insight that in their seriousness, they have not experienced the joy of being alive. Through the examples of these four types of men, Thomas affirms the brief and precious nature of being alive and defines how life should be lived—with passion, with joy, and with an elevating purpose not to be betrayed through inaction. Death is a “good night,” he believes, but dying should be resisted if a life, even a long life, has not been truly lived.