The Four Temperaments is a classical Greco-Roman theory of personality, articulated by Hippocrates (c. 400 BCE) and later systematised by Galen (2nd century CE), which links a person's character to a perceived balance of four bodily fluids, or humours. It sorts people into four temperament types according to which humour is thought to dominate.
An ancient pre-scientific theory of personality rooted in humoral medicine; historically influential but not medically valid or supported by modern science. (Hippocrates (c. 400 BCE), systematised by Galen (2nd century CE))