The exquisite European monastic herb gardens of the Middle Ages are frequently cited as ideal in the many Eurocentric gardening tomes (and, of course, the Brother Cadfael mysteries), particularly for their designs. They were always enclosed, contained long, easily accessible raised beds, which grew kitchen herbs, medicinal herbs, brewers’ herbs and strewing herbs.
What monks understood about using indigenous herbs for healing was originally pilfered mostly from women, mothers and midwives. As male-dominated church doctrine spread, the numbers of natural healers were reduced by an expanding guild of medical “doctors.” Scholarship reveals these Medieval physicians (the old word for doctor was “leech”) to have been a deadly, invasive, and aggressive bunch. Besides killing more patients than they cured, these early MDs persecuted and executed competitors, the herbalists who continued to practice. This apparently accounts for many of the notorious witch burnings during the Inquisition.
Meantime, medical knowledge was growing in the Islamic world, where science was flowering and ancient texts from the Greek, long lost to Europe, were being translated and put to use. This article from Aramco magazine gives a brief but fascinating history: http://www.saudiaramcoworld.com/issue/201101/pioneer.physicians.htm
Regardless of science and gender politics, many monks were aware that there is simply no adequate substitute for intimacy with Nature, the feeling of spiritual and physical wholeness that comes from working in the soil, particularly in the fragrant and palliative herb garden. Maybe this was why their gardens were dedicated to the Virgin Mary (Christianity’s sadly weakened feminine principle) and planted as her Paradise on Earth.
For a Medieval gardens refresher, refer to Andrew Wille’s Chelsea Physic Garden blog post — https://heathcollom.wordpress.com/2014/08/18/chelsea-physic-garden/ and take a look at The Great British Garden Revival — “Herb Gardens” begins at 30:15 (though Carol Klein on rock gardens is too delightful to miss). The herb episode takes place partly at the Chelsea Physic Garden.