Es- quirol, an early exponent of the functional point of view and of humane treatment in psychiatry, was born in Toulouse, France. After studying medicine at the University of Toulouse and Montpellier, he served as public health officer in the army. In 1794 he became Philippe Pinel’s assistant at Salpetriere, taking over as director in 1811. His first published work was his doctoral thesis, in which he proposed that emotional conditions were the source of many mental illnesses, a revolutionary concept in view of the prevailing opinion among doctors that insanity was caused by organic disorders, and among laymen that it resulted from possession by the devil.At Salpetriere Esquirol continued .Pinel’s humane approach and made systematic studies of his patients. In 1817 he established the first teaching clinic in psychiatry, and was probably the first investigator to use a statistical approach to the types and causes of mental illness. His studies revealed that a large percentage of his patients had been subjected to disturbing experiences, among which he mentioned monetary problems, unhappy love life, loss of position, and conflict with the mores of society. These statistics buttressed his theory that mental illness was primarily due to psychological factors.As a result of his clinical studies, Esquirol classified all psychoses into five categories, in contrast to the current tendency to give a different Latin name to every new symptom, a practice that produced more confusion than understanding. The five categories were mania, dementia, idiocy, lypemania, and monomania. He applied the term lypemania to melancholia with delusions, a condition that is now classified as depression. He also introduced the term hallucination, clearly differentiating it from delusion or false perception. His category of monomania applied to persons who were dominated by a single idea, a condition which is now recognized as paranoid schizophrenia. In addition, he anticipated the modem view that some disturbances of intelligence may be due to emotional disturbances rather than brain lesions.Esquirol left the Salpetriere in 1826 to become director of the Royal Sanitarium at Charenton, a semiprivate institution of the highest reputation. During the years that followed he had a profound influence on the practice of psychiatry in France. He drafted the Law of 1838, which legally established humane treatment for mental patients. He insisted that criminals were sick people suffering from monomania, and should therefore be treated like any other patient. He sent a memoire to the Minister of the Interior, stating how an institution should be run—a document which Zilboorg and Henry (1941) have called “one of the ablest and most influential in the history of administrative psychology.” On a trip to Italy he convinced the king that a newly built hospital was unfit for patients, and as a result it was turned into an armory, and a new structure was built according to Esquirol’s plans. In his own country he was responsible for the construction of ten new mental hospitals.Esquirol’s final work, published two years before his death, Les Maladies Mentales Considerees sous Les Rapports Medicates, Hygieniques et Medico-Le- gales, (Mental Disorders Considered in Their Medical, Hygienic and Medico- Legal Relationships) summarizing his lifelong teaching, has been called the first modem treatise on clinical psychiatry (Bromberg, 1959). In attempting to evaluate Esquirol, it would be hard to determine whether he made greater contributions on a practical or on a theoretical level to the development of modern psychiatry.