The common popular interpretations of William Ernest Henley's poem "Invictus" view the poem through the lens of Henley's personal struggles with tuberculosis and his secular humanist take on humanity's ability to survive in a universe that doesn't have any preoccupations or concerns for the preservation of life. Henley shows his opinion of humanity in his naming of the poem, as "invictus" is a Latin word that means "unconquered," "unsubdued" or "invincible."
One interpretation of the poem links parts of each stanza to an element of Henley's life. In this interpretation, Henley references his troubled early life, fight with tuberculosis and consequent leg amputation when he speaks of removing himself from a night that covers him "from pole to pole." Henley embraces the randomness of the universe, likening his position to being beyond his control; in his words, "in the fell clutch of circumstance." Yet he continues forward optimistically with his life, happy that his soul wasn't poisoned like his body: "I am the master of my fate: I am the captain of my soul."
The theme of the poem is survival and resilience. Henley takes an agnostic attitude toward religion, as he never specifies a specific god: "I thank whatever gods may be / For my unconquerable soul." He subtly reiterates this position when he opts to name himself as the captain of his soul instead of relinquishing control to a deity.