"Remembering pain is how you learn never to let the cause of it happen again" suggests that personal suffering serves as a valuable lesson. By recalling and reflecting on painful experiences, individuals can understand their mistakes and take steps to prevent similar harm in the future.
In James Patterson's book, "Confessions of a Murder Suspect," this idea may imply that confronting difficult memories can be a crucial part of growth and self-awareness. It emphasizes the importance of learning from past pain to make better choices moving forward.