The poem Do Not Go Gentle into That Good Night by Dylan Thomas is a call to arms against the disease that was claiming his father's life. The poet is pleading with his father, encouraging him to fight his illness and not let death take him away easily. The poem contains six stanzas in which the poet expresses his great compassion for his father, and his desperation to see his father fight to live.
The line "Do not go gentle into that good night" (Lines: 1, 6, 12, 18) appears four times throughout the poem. This line is essentially a call to action addressed to the poets dying father. He's saying, please do not just let yourself slip away into the darkness of death, rather struggle to survive. It is very interesting that the poet refers to the place his father is going as "that good night" yet insists that he not want to go there. In a sense the poet is saying that death is like a peaceful sleep where the lights of the world have gone and all that is around you is silent darkness.
Another line that is mentioned frequently throughout the poem is "Rage, rage against the dying of the light" (3, 9, 15,19) which is mentioned four times in the poem as well. This line is also a call to action addressed to the father of the poet. Rage or hatred toward death is frequently mentioned in this poem, "Old age should burn and rave at close of day;" (2) talks about how the elderly on their death bed should ignite with rage or hate against death. Rage is an ultimate form of anger, a violent anger. The poet, Thomas, states rage twice consecutively "Rage, rage against the dying of the light" (3, 9, 15, 19), letting the reader know that the extreme anger he wishes his father to have is deeper than just mere hatred. The poet wishes his father to hate death with such vigor that he does something about it. The rest of the line talks about the dying of the light, which basically portrays death as darkness separated from the light of the present living world.