The quote suggests a profound emotional struggle within the character, highlighting the connection between mental and physical well-being. It indicates that the character is grappling with feelings of illness that stem from his inner turmoil rather than any physical ailment. This reflects the theme of searching for identity and the impact of environment on one's psyche in James Joyce's work.

In "A Portrait of the Artist as a Young Man," this concept of being "sick in the heart" reveals the protagonist's intense sensitivity and the complexity of his emotional state. It underscores the idea that true discomfort often originates from unresolved feelings and existential questions, emphasizing Joyce's exploration of the human experience and the inner conflict of the artist.