The overall tone of “Invictus” is determined and defiant. Readers can sense this tone already in the title, which is Latin for “unconquerable.” The concept of unconquerability powerfully announces the poem’s central theme, which concerns the indomitable nature of the human spirit. The speaker addresses this theme at length, describing their struggle to assert control over their own life and fate. Given their account of their struggle, the speaker’s perspective is clearly hard won. A life lived in adverse conditions has forced the speaker to develop a capacity for self-determination. It has also required the speaker to reject everything that no longer serves them. It is precisely this combination of determination and defiance that gives the speaker’s language a self-assured quality. The strong rhythm of the meter and the regular use of rhyme also contribute to this feeling of defiant self-confidence. As an example, consider the final stanza (lines 13–16):

     It matters not how strait the gate,
           How charged with punishments the scroll,
     I am the master of my fate,
           I am the captain of my soul.

After dismissing traditional Christian ideals of piety and judgment, the speaker defiantly asserts that no one can determine their fate and control their life—no one, that is, but the speaker themself.