Relationship between life and death. inside, outside: No information about this but it is two different photographs put together to create a half skull, half face image. That heavily relates to the theme of inside, outside and in between.
When you feel bad your mind continues to focus on all the parts of your life that seem to not be working. Then you feel even worse. This all continues until you wake up to the fact that your self-image is just a mental idea. It is just a concept