The speaker of "Do Not Go Gentle into That Good Night" is a son about to lose his dying father. From the thoughtful style of the writing, it can be assumed the speaker is at least a young adult, though he could possibly be older. As a result of his parent's impending death, the speaker's tone is somber and desperate. He appears to have accepted that his father will die no matter what he does or says, but he wants his father to go out fighting. Rather than hoping he will peacefully and passively accept death, as is commonly wished in most poetry about death, the speaker hopes his father will "rage against the dying of the light," recapturing the energy of his prime.
This motivation fuels the speaker's rhetoric throughout the poem. He catalogs all the different kinds of men who have fought against the end of life with their final moments: wise men, good men, wild men, and grave men. This extensive list suggests the speaker is an eloquent, observant person. The length of these descriptions also shows the desperate nature of his wish that his father die fighting: he is hoping the examples of those who have gone before him will convince him to face death with defiance.