In Patrick O'Brian's "Post Captain," the character development often reflects the complexities of maturity and emotional resilience. As individuals grow and adopt a more mature demeanor, they may unintentionally distance themselves from the pleasures that once brought them happiness. This transformation can lead to a sense of indifference, which highlights the bittersweet nature of growing up. The pressure to appear strong and unflappable often comes at the cost of joy and enthusiasm.

The quote emphasizes that the façade of invulnerability can hinder genuine emotional experiences. While maturity is generally seen as a positive trait, it can also result in a loss of connection to the joys of life. As characters navigate their journeys, the tension between maintaining a composed exterior and embracing authentic feelings becomes a central theme, illustrating how the pursuit of maturity can lead to unintended consequences in personal relationships and overall happiness.