The name "melancholia" comes from the old medical belief that there are four basic liquids in the body (called humors). According to this belief, diseases happen when the humors are not balanced correctly in a person's body. Humors were also thought to determine personality types. According to Hippocrates, melancholia was caused by having too much black bile in the body. The name "melancholia" means 'black bile'. It comes from the Ancient Greek words μέλας (melas), meaning "dark, black", and χολή (kholé), meaning "bile".