The first ring of the diagram identifies the zodiac signs with the related humors and elements. The four humors played a large part in medieval lives. A person whose humors were in balance was healthy; unbalanced humors caused illnesses. Basically, the human body was believed to be made of four substances: blood, yellow bile, black bile, and phlegm. Each substance was linked to a season, an element, an organ, a temperament, and other qualities. For example, black bile was related to autumn, earth, the gallbladder, melancholy, and was considered to have cold and dry properties.
People also believed the zodiac signs presided over parts of the body and were associated with an element. The bull, Taurus, ruled over the throat, neck, thyroid gland, vocal tract; and was affiliated with black bile (melancholy).
These complex astrological charts were used to determine diagnoses and treatments, which were based not only on the actual physical symptoms, but also temperaments and birth signs. This diagram illustrates the medieval worldview in which everything was connected in a tenuous balance, including mankind and his health (microcosm), and the Earth and the universe (macrocosm).