A Spanish-language scholarly study of modern psychiatric thought, this work examines the intellectual legacy of Henri Ey, a major twentieth-century French psychiatrist. Through a historically informed and clinically grounded approach, it explores the relationship between psychiatry, psychology, and psychoanalysis, showing how ideas about mental illness, consciousness, personality, and therapeutic practice evolved across modern European medicine. The book is intended for readers interested in the history of psychiatry, the development of clinical concepts, and the philosophical questions surrounding mental health. Its focus is analytical rather than narrative, offering a concise introduction to the theoretical currents that shaped psychiatric thinking in the twentieth century.