The themes of confidence and self-doubt within a larger question of identity are central in Joseph Conrad's story. The young captain lacks self-confidence in his leadership abilities and even in his seamanship. His emotional investment in his new role as captain is so strong that it threatens to overwhelm his common sense. The captain's wishes to be a strong leader—not merely to seem like one—are part of his secret. He keeps "secret" within himself this "ideal conception of one's own personality...."
Throughout the story, Conrad builds on this idea of the secret ideal that the captain tries to hold onto "faithfully." He finds it not among any of his crew, an undistinguished lot "simply... equal to their tasks," from whom he distances himself. Rather, this ideal appears in the figure of Leggatt. Seeing him first in the water, thinking him not just dead but headless, the captain quickly perceives him as his "double." As he hears the other's tale, his admiration and dismay grow simultaneously—would he himself ever kill a disobedient man?
Once he decides to release Leggatt, to free himself from that man and his dark secret, his understanding of his role is deepened. He knows that he will be faithful to the best side of the leader personality that he "set up for himself." And in guiding them safely near the shore, he symbolically assumes the heroic savior quality he craved.