The poem's first line is a directive, and the same wording ends several more segments (in forms known as tercets) with different context/s depending on the preceding words, for example, "Wild men who caught and sang the sun in flight, And learn, too late, they grieved it on its way, Do not go gentle into that good night." This could mean the poet is speaking of men who perform such deeds, or it could suggest the poem is speaking to them directly, with the line "do not go gentle into that good night" again being used as a directive. The tercets all contain slightly different themes exploring potential areas of regret or uncertainty that people may experience upon confronting the spectre of mortality.
The poem addresses those who contemplate mortality, whether their own or that of others, but the tercets separate the potential subjects into wise men, good men, wild men or grave men, with admonishments for each. It has also been suggested that the poet is writing directly to his own father on his deathbed. The language describing the strength of character and noble deeds of those in old age is a reminder to celebrate the lives of those who are dying or who have died, and to make the most of our lives to lessen the pain and fear of death's inevitable arrival.