For medieval physicians, the mnemic apparatus of choice was what is sometimes today known as a folding almanac or a belt book. There are thought to be just 29 such almanacs that have survived to the present day. The almanacs contained detailed astrological calendars, lunar tables, diagrams of the human body and so on necessary for the practice of lunar medicine during the 15th century. They were small and strung onto a cord that attached to a physcian’s girdle or belt.
Llewellyn's 2017 Astrological Calendar: 84th Edition of the World's Best Known, Most Trusted Astrology Calendar