Through The Looking Glass

If I asked you what came to mind when I say ‘medieval glass’ you might reply the stained glass at Chartres Cathedral, or perhaps the inner casing of a holy reliquary, or maybe even an elaborate goblet set on a royal dais; but it is quite unlikely that you’d think of a urinal.

Urinal, 1400s, Musuem of London

Glass was an important material in medieval medicine and science. Glass flasks were used because of their transparency and because they did not contaminate their contents by corroding. Glass instruments were used in alchemy to prepare acids, to distil alcohol, and in medicine for uroscopy.

Uroscopy was the diagnosis of a disease through the examination of the colour of a patient’s urine. The urine flask became one of the symbols of the physician’s trade, and a doctor can often by identified in illuminated manuscripts by their possession of a glass flask.

Physician teaching students, Paris, 1300s,
(British Library, Harley 3140, f. 32v).

Physicians often owned charts that catalogued the different colours of urine and the illnesses to which these could be linked. For example, blue urine was associated with indigestion and black urine was meant to indicate death.

Diagnostic chart, England, c.1406,
(British Library, Harley 5311).

It is important to remember the smaller, everyday objects and not just the glamorous and glittering jewels of medieval life. But perhaps the worlds of stained glass and urinals were not so distinct from each other. In the Becket Miracle Windows at Canterbury Cathedral physicians were depicted consulting their urine flasks, but the message was to rely not upon your physician but rather on the healing power of the saint, even in those cases when your urine was black.

Chartres Cathedral,
Constantine has leprosy and consults a physician.