Like Hippocrates, Galen set about classifying all illnesses in terms of excesses of various fluids. Inflammation—a red, hot, painful distension—was attributed to an overabundance of blood. Tubercles, pustules, catarrh, and nodules of lymph—all cool, boggy, and white—were excesses of phlegm. Jaundice was the overflow of yellow bile. For cancer, Galen reserved the most malevolent and disquieting of the four humors: black bile.
