Galen developed the Theory of the Four Humours to include the idea of balancing the humours by using the Theory of Opposites. For example, he suggested that too much phlegm, which was linked to water and the cold, could be cured by eating hot peppers; a fever, or an excess of blood, could be treated with cucumber, which would cool the patient down when eaten. Galen also theorised that the circulatory system circulated blood generated in the liver, and the blood was then distributed around the body.