an obsolete speculative theory, according to which disturbance of the body juices (blood and lymph or, according to Hippocrates, blood, mucus, yellow bile, and black bile) is the cause of all diseases. Among those who supported the theory were Galen and Ibn Sina, and later Paracelsus, van Swieten, and K. von Rokitansky. Contemporary medicine, though attaching great importance to humoral regulation in the origin of diseases, does not regard it as something isolated from functional and structural changes in other constituents of the body and from environmental influences.