The essence of self-knowledge is a recurring theme in Robert Kurson's "Shadow Divers." The characters contemplate how most men live without a deep understanding of their true selves. They argue that qualities such as nobility or bravery are often based on personal perception rather than objective truth. It is only through significant challenges and tests that a person can genuinely discover who they are beneath their beliefs.

This idea emphasizes the importance of facing adversity to gain insight into one's character. Until confronted with difficult situations, individuals may hold a flawed or superficial view of their virtues. The narrative suggests that true courage and integrity come to light only when one is pushed to their limits, highlighting the transformative nature of life’s trials.