Hartmann argues that the unconscious mind is the primary reality, and that the conscious mind is merely a small part of it. He believes that the unconscious mind is responsible for all of our thoughts, feelings, and actions, and that it is the source of our creativity and our drive to progress.

Hartmann divides the unconscious mind into three levels: the personal unconscious, the collective unconscious, and the transpersonal unconscious. The personal unconscious contains our repressed memories, desires, and experiences. The collective unconscious contains the shared experiences and beliefs of all humanity. The transpersonal unconscious contains the universal truths and principles that underlie all of reality.

Hartmann believes that the unconscious mind is the source of all creative ideas. He argues that the unconscious mind is constantly working on new ideas and solutions, and that these ideas and solutions can be accessed by the conscious mind through dreams, intuition, and inspiration. He also believes that the unconscious mind helps us to solve problems and find new solutions by allowing us to see things from a different perspective. Finally, he believes that the unconscious mind allows us to connect with our inner selves and express our true selves by allowing us to access our repressed memories, desires, and experiences.

Hartmann believes that the unconscious mind can contribute to the development of mental illness by repressing memories, desires, and experiences that can lead to anxiety, depression, and other mental health problems. He also believes that the unconscious mind can be used to treat mental illness by allowing patients to access their repressed memories and experiences and to work through them in a safe and supportive environment.

Hartmann's ultimate goal in writing The Phenomenology of the Unconscious was to achieve a deeper understanding of the human condition. He believed that by understanding the unconscious mind, we can better understand ourselves and our place in the world.