Folio 9r diagrams the relationship between the year, the seasons, the four elements, and the four humors (sanguine, melancholic, choleric, and phlegmatic). Written in the diagram on the bottom of the page are the correspondences between each system. At the top, going clockwise, Ignis calidus et siccus estas calida et sicca, “Fire is warm and dry, summer is warm and dry”; Aer calidus et humidus ver humidus et calidus, “Air is warm and moist, spring is moist and warm.” The four elements – fire, air, water, and earth – were supposed to originate from the four primary Aristotelian qualities, and each of them corresponded to one of the four humors in the human body – yellow bile, blood, phlegm, and black bile. In turn, the proportions of each of these humors were supposed to determine the health and temperament (or personality) of an individual. The diagrams are colored primarily with red, green, and yellow. On the right side of the page, the text describes the diagrams. There are no marginal notes on this leaf, but there is a large discoloration on the bottom-right side and some discoloration within the bottom diagram.
The theory of the four humors was first put forth by the Greek Father of Medicine, Hippocrates, in the 4th century BCE, and further described by Galen in the 2nd century BCE. The idea was revolutionary: Disease used to be considered divine punishment, and this theory was one of the first to formulate the notion that diseases were caused by something environmental or physical. The theory also implied that disease could be prevented by managing the proportions of the four humors inside of the body. The practices of bloodletting as well as regulating consumption of certain types of food have their genesis in this belief. This folk medicine tradition was inherited by medieval doctors. For further descriptions, see the YouTube video below.