The history of medicine, a fascinating subject, shows how people began to understand more and more about the corporeal body. Herbs played a big role in the evolution of this understanding, and medieval monasteries encapsulated this knowledge:
The curriculum of these cathedral schools embraced originally the Trivium, (arithmetic, grammar, music), and the Quadrivium (dialectics, rhetoric, geometry, astronomy). Charlemagne, in the Capitulary of Thionvillc (805), ordained, however, that medicine also should be taught (as already stated) under the name of Physic. How far the Arabian schools (and the Roman higher schools) served as patterns and & stimulus in this matter, it is not easy to determine. That both exercised some influence, seems probable, when we remember that Charlemagne had dealings with the Arabians, and frequently built upon Roman foundations. In the monastic gardens medical herbs, such as althaea, water mint, squill, savine etc. were always to be planted. In the monastic garden of St. Gall e. g. in the year 820 the following herbs were cultivated: lilium, rosa, salvia, sisymbrium, ruta, cumimim, pliidiola, luhestico, pulegium etc. Still more! This monastery possessed a chamber for very sick persons, a pharmacy, and a house for the physicians, with a residence for the regular physician of the monastery.*
In northern Europe, cooks still use Sisybrium officinale (also called Hedge Mustard) in salads and mustard pastes. (I’ve got some growing all over the edges of my backyard right now.)
From Outlines of the History of Medicine and Medical Science, by Johann Herman Baas (1889).