Ever look at your pee and think…hm…what does this all mean? You’re not alone.
In the Middle Ages, the color of a person’s skin, hair, or urine was used to diagnose illness. These outward manifestations were thought to reflect underlying character, one’s “temperament” or “humor.”
Whether choleric (yellow), phlegmatic (white), sanguine (red), or melancholic (black), a person’s “humoral” state was understood from the proportions of the four Aristotelian elements (earth, air, fire, and water) within the body.
The humoral theory found in medical texts on uroscopy (the diagnostic study of urine) also can be found to underlie some medieval craft recipes. For instance, Theophilus Presbyter prescribed the use of the “urine of a red-haired boy” to harden iron tools, uniting the perceived “fiery” nature of redheads with the arts of the forge or metalworking.