Rhazes (865–925) was the first physician to show that the theory of four humors was wrong, in his writing "Doubts about Galen". He carried out an experiment which would upset this system: 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. Avenzoar (1091–1161) carried out an experimental dissection and autopsy to prove that the skin disease scabies was caused by a parasite. This discovery upset the theory of humorism. The removal of the parasite from the patient's body did not involve purging, bloodletting, or any other traditional treatments associated with the four humors. Ibn al-Nafis (1213–1288) then discredited the theory of four humors after his discovery of both pulmonary circulation and coronary circulation.