After failing t convince Strickland to return to his wife and family in London, the narrator contemplates Strickland's conscience and how it aligns with societal expectations. The narrator uses a metaphor to compare conscience to several professions:
I take it that conscience is the guardian in the individual of the rules which the community has evolved for its own preservation. It is the policeman in all our hearts, set there to watch that we do not break its laws. It is the spy seated in the central stronghold of the ego.
Conscience can be a guardian, a policeman, or a spy—all professions that are grounded in control. Therefore, conscience is something that controls people's minds based on societal expectations and rules. People generally act morally and responsibly because society's rules dictate that they should act in this manner. Even when no one is watching, people often take the moral high road, and the narrator believes it is the "policeman in all our hearts" planted by society that influences people to do so.
Therefore, Strickland's ability to ignore his conscience and do terrible wrongs in pursuit of art perversely demonstrates his strength of character, as he is able to overcome the control of the guardian. Strickland is not considered moral—in fact, he is a blatant rule-breaker, but he does so with confidence. It is this confidence that paints him as an artistic hero in the narrator's mind. After all, the novel is a piece of admiration and fascination about Strickland, someone the narrator wishes he could be as a fellow creative.
After Blanche criticizes Strickland's art, Stroeve claims that art is something to be enjoyed only through one's own recreation of it. With a metaphor, Stroeve compares the beauty of art to a melody one must sing:
Beauty is something wonderful and strange that the artist fashions out of the chaos of the world in the torment of his soul. And when he has made it, it is not given to all to know it. To recognize it you must repeat the adventure of the artist. It is a melody that he sings to you, and to hear it again in your own heart you want knowledge and sensitiveness and imagination.
When Stroeve compares beauty to music, he implies that beauty is something that must be actively created in order to be enjoyed. Beauty is not something that can be seen but instead something that must be felt through creation and imagination. This perspective aligns with the revelation of Strickland's blindness at the end of his life. Even without sight, he was able to produce a masterpiece representative of the Garden of Eden. Such a feat suggests that art and beauty is something created through feeling and one's own inner vision, not something merely spectated.