People don't value goodness as much as they should.

The narrator of “Salvatore” aims to determine whether the story of a good, "ordinary fisherman" could hold readers' interest. By beginning and ending the story with this frame, Maugham hints that even readers themselves are more interested in villains and conflict than with goodness. Aside from this overall assumption that a good but average man's life story is uninteresting, several moments in the story demonstrate characters prioritizing less important traits over goodness. For example, the girl betrothed to Salvatore (as well as her parents) value financial potential more than goodness. Even Salvatore's first reaction to Assunta's proposal is to focus on how she looks instead of who she is. People in the story value physical beauty and financial success, but in the end, it is goodness that keeps Salvatore happy. "Salvatore" is proof that a story about an ordinary man can keep readers' interest, and the final lines ask readers to consider why more stories aren't written about the rare quality of goodness.

Appearances can be deceiving.

Throughout the story, the narrator shows that people’s assumptions based on appearances often keep them from seeing the truth. The most obvious example is Salvatore, who appears to be an ordinary fisherman with an illness living a difficult life, but really possesses what is deemed the rarest and most valuable trait in the world: goodness. When imagining a character who represents goodness, Maugham describes not a perfect human, but instead an average fisherman to show that goodness is often found in people and places we least expect. 

Even Salvatore himself is guilty of being prejudiced by his own assumptions. He assumes Assunta is too “ugly” to be his wife. However, the woman he compares to the "devil" actually becomes a capable, loving wife to him. The girl Salvatore first wanted to marry assumes Salvatore can't provide a good life, even as he promises that he can. Her assumption that he can't provide for her (which seems to be planted in her mind by her parents) keeps her from recognizing Salvatore's true potential as a husband. And the girl herself, though very beautiful, proves to be selfish and insensitive in her blunt treatment of Salvatore, further underscoring how appearances can be deceiving.

Outlook determines happiness.

Salvatore's superpower is his ability to appreciate the parts of his life he is grateful for and to accept life's defeats without resentment. This outlook allows him to truly enjoy his life even though it's not what he envisioned for himself. Salvatore has the ability to focus on the positive even in the face of setbacks as is evidenced by his reaction to the news that he has developed a type of rheumatism that will affect him for the rest of his life. His complete focus on the news that he's going home, and his disregard of the reality of his tragic diagnosis, demonstrates the way he approaches life. He has every reason to be angry about how circumstances out of his control have affected his life. None of the things that happen to Salvatore are brought on by his own actions. First, his required military service and then the illness he acquires fulfilling his duty keep him from the marriage and life he wanted to build. However, Salvatore's goodness lies in his ability to find joy and gratitude in his life, and his goodness allows him to accept whatever circumstances come his way.