Medieval physicians are usually portrayed in a library surrounded by medical textbooks, but this is misleading. Medical practitioners during the Middle Ages frequently left their book-lined offices to examine patients in hospitals, clinics and in their patients' own homes. But what about all that information left in the libraries? Though they had no Merck Manuals, medieval physicians often carried small fans made of folded parchment pages on their belts. These leaves contained ready reference guides which helped the physician perform the necessary functions of diagnosis and therapy. Fastened together with cloth and leather, these small memory aids are called "belt books."

Here we have two illustrations from a fourteenth century belt book which is believed to have been copied at York in the north of England about 1364. The first image is designed to aid the physician in making a diagnosis by analyzing the color of the patient's urine. The second figure facilitated therapy by indicating points at which the practitioner could effectively tap his patient's blood. In addition to these images, the York belt book also contains a table of the movable feasts from 1364 to 1462, a calendar, a list of lunar and solar eclipses, and a chronology.

These images (folios 8 & 9) from the Rosenbach Manuscript - MS 1004/29 are presented with the kind permission of The Rosenbach Museum & Library.

• Folio 8 - [Bloodletting figure or phlebotomy man].
• Folio 9 - [Urine Wheel, complete].