International audienceExamination of the patient's urine has long played an important role in medical semiology. It was considered that this fluid, also called "water of the body" by euphemism, offered, at its exit of the organism, a recording of the internal mechanisms for who knew how to read them. Among the criteria to be observed, color was the first one, by its obvious sensitivity. But this sign was not considered by all as absolutely reliable, and throughout the period, reservations were expressed on the credit to be given to the urine, including its color, and even the number of tints that this liquid could take was questioned. The Paduan physician Michel Savonarole is one of those who expressed doubts, while recognizing the necessit...