Being frightened

According to medieval theories of physiology and medicine, the human body was made up of four main fluids, or "humours" - blood, phlegm, choler (yellow bile) and melancholy (black bile). These fluids were believed to determine a person's appearance and temperament, depending on their relative proportions in the body. According to the theory, blood was the hot, moist element, but extreme fear could cause it to become cold or even curdle, hence the expression "make your blood run cold" or a "blood-curdling scream". - The Real McCoy, Georgia Hole

According to medieval theories of physiology and medicine, the human body was made up of four main fluids, or "humours" - blood, phlegm, choler (yellow bile) and melancholy (black bile). These fluids were believed to determine a person's appearance and temperament, depending on their relative proportions in the body. According to the theory, blood was the hot, moist element, but extreme fear could cause it to become cold or even curdle, hence the expression "make your blood run cold" or a "blood-curdling scream". - The Real McCoy, Georgia Hole

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