Medical Renaissance
During the Medical Renaissance, several important physicians helped to prove this theory wrong. The first was a Persian physician called Abū Bakr Muḥammad ibn Zakariyyāʾ al-Rāzī  (865-925; he was also called Rhazes). In his book Doubts about Galen, he described doing an experiment to test Galen’s theory about what controls body temperature. He inserted a liquid with a different temperature into the body. This would result in an increase or decrease of bodily heat, which resembled the temperature of that particular fluid. Rhazes noted that a warm drink would heat up the body to a degree much higher than its own natural temperature. The drink would therefore trigger a response from the body, rather than transferring only its own warmth or coldness to it.