13th and 14th Century Medical Physics
This will not be a complete treatment of medieval science, just an overview of the concepts that seem to have the most relevance for the medieval medical practitioner.
It is important to understand that not all of these concepts were fully understood, even in the Middle Ages. The physics that was inherited from Plato did not quite match what was inherited from Aristotle, and both of these pagan systems had to be harmonized with Christian faith. The great thinkers of the Middle Ages wrestled with these inconsistencies, and also attempted to deal with matters that they knew very well were not fully explained by any of the great philosophers.
The old chestnut “how many angels can dance on the head of a pin” doesn’t do justice to the real dilemmas that medieval philosophers studied.
This is called the Doctrine of Signatures. Plants and animals have the “signature” of their use in their form. A plant that strengthens the blood might have red sap. The cartilage in the long-lived stag’s heart is taken to strengthen the human heart. (Getz xix)
However, most medieval medical treatments were designed according the sophisticated science of the 4 elements. (Getz)
This invisible element is the most energetic. It is also known at the Prime Matter or first matter because from it the other 4 elements were created. Furthermore, its energy permeates all of the material world, giving energy to the other elements and everything made from them. It is essential for life, and is the basis of the vital force. See Anatomy and Physiology.
Each element has its natural sphere in the terrestrial sphere. Earth, being the heaviest is in the center, surrounded by water, then air, and over all, fire. (Things in the celestial spheres, the moon, sun, etc. are made purely of ether.)
Most objects tend fall toward the earth, because they contain the element earth and are trying to get back to their natural place. Things such as smoke or flame rise because they consist primarily of air or fire, and therefore are they trying to get up to their natural sphere.
[Illustration of spheres will go here. Someday.]
Earth is the central element. It has the greatest weight and the other elements gravitate toward it. It is at rest, the “still center”. It gives objects their stability and outward form. It is cold and dry.
Water is just outside of earth, but inside of air. It is a “simple substance.” It is cold and moist in temperament. It is easily dispersed and takes the shape of its container. In objects, it allows them to be formed and shaped and spread out. It dispels, or rules, dryness. It protects dryness from crumbling (as moist earth or mud), and likewise, dryness prevents moisture from dispersing or draining away. Thus the elements of earth and water are interdependent and interacting.
Air is positioned above earth and water, but below fire. Its temperament is hot and moist, and it functions to make objects finer, lighter, more delicate, enabling them to ascend to higher spheres. It is the agent of the breath and makes possible the involuntary movements of the body.
Fire is positioned above the other elements. It, like water, is a “simple substance”. It is hot and dry in temperament. Its role is to rarefy, refine, and intermingle substances. It can penetrate and ride through (?). It is able to overcome the coldness of earth and water, and so maintains harmony among the elements.
The elements of earth, air, fire and water are to be understood metaphysically, not literally. They describe the primary matter that is then combined to make the things we actually observe, from mountains, to rivers, to campfires. The campfire is not the element fire, because the element of fire is the potential for fire in substances, such as the wood being burned. And in a more simplistic sense, a river is not made of just the element water, but to the extent that it is warm, foamy, silty, etc. it also contains the other elements.
The 4 elements are determined by 4 qualities: hot, cold, dry, moist. As noted above, earth is cold and dry. Water is cold and moist. Air is hot and moist. Fire is hot and dry. And via these qualities many, many correspondences are found: the four seasons, the four ages of man, the four cardinal directions, the four winds, the four periods of the day, etc. All the physical objects in the world partake in all four elements to varying degrees, and through them are related to and influenced by the heavenly bodies of the zodiac, which also partake of the elements.
In the body, these 4 elements and 4 qualities become the 4 biological humors that are the basis of health and disease and will be discussed further in the section on Anatomy and Physiology.
The four elements are continually moving in the body. This continuous process of change can be cyclical or progressive. Intake and elimination of food is a cyclical process. Growth is a progressive change, even in something like a cancerous tumor.
Table of Elemental Correspondences (from Unani):
To and fro
Digestion, voluntary action
Some might argue that this was more of a metaphor or memory mnemonic than a full-featured scientific theory, but it did have practical consequences.
Imbedded in the macrocosm-microcosm relationship was the idea that the macrocosm influenced the microcosm. This was pretty obvious. The Sun warms the earth. The moon governs the tides. The zodiac determines the seasons. And all of the above affect human health via the 4 elements, and their correspondences. See the discussion of Regimen.
During the Middle Ages, the relationship between the cosmos and the human body was worked out in great detail.
Accordingly, the study of astrology was important for the medieval medical practitioner as he or she tried to understand the cosmic influences on human disease, and work with them to maintain health. Various tools such as the “Zodiac Man” and the “volvelle” were designed to help. They will be discussed further in the article about Diagnosis.
Material causes: the physical substance, or material. Medically, these are the involved organs or body parts, and the humors. (You can’t make a boat without wood.)
Efficient causes: the forces that physically act on the material causes. Medically, these are environment, evacuation and retention, aging, activities, sleep, etc. (Your boat is affected by wind, water currents, etc.)
Formal causes: the goal or end results. Medically, the physical constitutions/complexions/temperaments, and the virtues or problems that result from them. (Shipwreck, going off course, safe arrival, successful trade transaction, etc.)
Final causes: the operations, procedures, techniques, used to control all of the above. These are the subjects of the doctrine of medicine, how health may be preserved and sickness cured, the rules of eating and drinking, choice of air, doctoring with medicine, etc. (How to build a boat, how to navigate a course, etc.)
How do you know what an animal is? You compare it to the “idea” of a dog, cat, etc. that you have in your mind. This perfect “idea” of a dog does not depend on accidental features such as fur color, size, age, etc. that are changeable, variable and, therefore, imperfect. You are able to identify a dog as a dog, even when it only has three legs.
Everything now existing in the physical realm is a replica of the perfect forms that exist in a second realm of ideas. This realm of ideas has a real, but incorporeal, eternal unchanging existence.
Plato stated that the world of forms or ideas was “primary”, unchanging (and therefore perfect) and more real than the material world. The objects in the material world were “secondary” - transient shadows of the real objects. We just think they’re more real, because they are what we grow up with.
True knowledge comes from contemplating and understanding the ideal forms, and the ultimate goal is learning how to manipulate material objects to get them closer to the ideal forms. (Alchemy is the most obvious example.)
Plato’s theory was controversial, (because it was different that Aristotle) but influential, and it was fairly simple to modify it to agree with Christian beliefs about the divine creator and an imperfect world. The concept of the “idea” helps in understanding the 4 elements, the 4 qualities (and therefore, the 4 humors). The 4 elements and 4 qualities may be considered part of the realm of “ideas” and ideal forms, while rocks, lakes, campfires, etc. are their imperfect, impure replicas in the material world.