Mental illness has been understood and interpreted differently across historical periods, shaped by prevailing cultural, religious, philosophical, and scientific ideas. In ancient civilizations, mental illness was often explained through supernatural and spiritual beliefs. In Mesopotamian, Egyptian, and early Hindu societies, abnormal behavior was attributed to possession by evil spirits, displeasure of gods, or demonic forces. Treatments therefore involved rituals, prayers, exorcism, and offerings to appease supernatural powers. In ancient India, the Ayurvedic system recognized mental disturbances as imbalances of bodily humors (doshas) and emphasized holistic treatment through diet, meditation, herbal remedies, and moral living, reflecting an early integration of biological and psychological understanding. In ancient Greece and Rome, a more rational approach emerged. Hippocrates rejected supernatural explanations and proposed that mental illness resulted from natural causes, particularly imbalances in the four bodily humors—blood, phlegm, yellow bile, and black bile. He categorized conditions such as mania, melancholia, and hysteria and advocated humane treatments like rest, diet, and exercise. Aristotle emphasized emotional regulation and environmental influences on mental well-being. Roman physicians such as Galen further developed humoral theory and stressed the role of lifestyle in maintaining mental health. During the Middle Ages in Europe, supernatural interpretations