What is the theme in Black Like Me by John Howard Griffin?

Self loathing is a theme. Griffin often speaks about the depression, loneliness, and anger that he felt while he was a black man. As his time wears on, he cannot stand the face that stares back at him in the mirror. Because of this skin, he cannot seek advancement. As an educated man who has all the right credentials, he can't even get a job as a bookkeeper. All doors are closed to him. The feeling of sickness and loneliness overwhelms him. As Griffin begins to talk and connect with black leaders, he realizes that this loathing also plays into whites' ability to oppress blacks.