I read this poem as more about a son's attitude to his father than about advocating that people generally should fight against their doom. The poet cannot bear to see his father resigned to death. He wants him to show at least as much fight as other old men have done. I believe that he idealizes his father, feels very distressed, disappointed and perhaps betrayed by the fact that his father is dying, and believes that those feelings will be relieved if his father makes it clear maybe by tears, rage, that he doesn't want to die. That is the only part in the poem I will change because while reading the poem I simply thought to myself that he was thinking of his fathers cancer and how he was about to die. I believe the poet has an anger that he has no way of controlling and it seems that he wants to fight off his fathers cancer on his own. He knows he can not control his fathers dying so he tells his father to not give in and go easy into that never ending darkness. To not let go of the light and give up on him. To live life until there is no more to live. I only wish at some point in the story the poet would have added his fathers answer to his son. Something that would show the son that the father wants to be strong and continue to live to the fullest, something that would show us that the father dose not want to not go gentle into that good night.