Adler the optimistic doctor, who never gave up trying to find a cure for the patient, devoted himself to the careful examination of the nervous character. The findings of this research are presented in this book. His fellow doctors rightly characterized every mentally ill person as having a nervous character, because indeed, as proven in this book, the nervous character is the prerequisite for every mental illness, which is nothing more than a quality or symptom of the nervous character. Neurosis and psychosis manifest themselves on the nervous character at a certain time in a person's individual life. [...]