 Opposition to class , death and its impacts , experiencing adolescence , sacrifice , love , friendship , loyalty , prejudice , and racism are constant themes of the series . In Harry Potter and the Chamber of Secrets Harry 's consideration and respect for others extends to the lowly , non @-@ human Dobby and the ghost Nearly Headless Nick . According to Marguerite Krause , achievements in the novel depend more on ingenuity and hard work than on natural talents . 
