How does the excerpt from incidents in the life of a slave girl reflect the theme of self-reliance?

In the book, Linda(the protagonist) has no one in the world but herself. Literally. Her parents both died when she was younger and she was left to a horrible and sexaully abusive slave owner. She had to learn how to stand up for herself and care for herself from a very young age. When she had a love affair with the neighbor her life became even more chaotic. She then not only had to care for herself, but the two children that came out of the affair. She had to rely on herself and her physical and mental strength to get her and her children freed. In the end no one ended up helping her aside from herself, she had become successful(for a slave) and had her kids in a safe place, both of them getting an education, and she did this all by herself. 

The author's purpose is to be persuasive