Obtaining a grounded understanding of psychiatric phenomenology, otherwise known as "descriptive psychopathology," is the most important step in diagnosing and properly treating people with mental health concerns. How then can this be best accomplished if not by teaching the fundamentals of descriptive psychopathology in a manner that the knowledge can be easily absorbed? Hence the term "from first principles," as appearing in the title. There is no jargon and no superfluous descriptions of psychiatric phenomena that inadvertently confuse students from the actual acquisition of knowledge. Passing term examinations and board examinations in psychiatry is the ultimate goal of medical students and psychiatric residents. This book is a gold mine of high-yield materials for these examinations.