The ancient Greeks believed that abnormal behavior or mental illness was caused by demonic possession or punishment from the gods. The Greek physician Hippocrates (460-377 BC) denied this and stressed that psychological disorders or psychopathology could be treated like a disease or injury. He believed that abnormal behavior and illness resulted from internal or biological causes, such as brain dysfunction, head trauma or genetic malfunctions. He is often described as the Father of Medicine in the modern Western world.