Opposition To Galen's Medical System During The Renaissance

In the last section I explained that Descartes’ mechanical physiology opposes to the traditional Aristotelian-Scholastic’s physiology, founded on Galen’s elementary qualities. However, it is important to remark that the opposition to this sort of explanation was not a novelty, since we can find an opposition to Galen’s medical system from the Renaissance with the development of natural magic. In general, natural magic is based on the assumption that bodies have certain qualities which make them to act upon one each other. These qualities are not manifest by themselves, but we can recognize their existence because we perceive the effects they cause. In this sense, the natural magic tradition propose that bodies have certain occult qualities
According to John Henry, such a criticism was caused for two main reasons: in the first place, the discovery of medical plants from the New World; and, in the second place, the epidemic character of infectious diseases. Thus, for him, there are internal and external issues which could not be solved by the Galenic conception of medicine and they make possible the development of the medical alchemy with its basic explanatory principles: the occult qualities and the vital
Accordingly, it was possible to explain the action of a plant or an animal on the human body for its elementary constitution but, mostly, because it had been already explained through an obiter dictum from Aristotle, Dioscorides, or some ancient authority. In this sense, the discovery of the New World presented a considerable problem for the fifteenth and sixteenth-century Galenic physicians. As Henry explains: ‘the tendency of explorers was to bring back just those plants which were deemed by native populations to be most useful in curing disease. More often than not, European doctors could not decide how, or even whether, such unknown drugs worked on the four humours of the body’ (2008: 23). As a consequence, medical thinkers developed a strong commitment with observation and experimentation that was progressively included in modern science. Nonetheless, the impossibility of accounting how New World’s materia medica acts upon the human body to heal it opened the door to the acceptance of the alchemical idea that bodies have certain qualities which allow them to produce determined effects when they interact each other. Thus, vital principles and occult qualities began to be increasingly accepted as valid explanations of the action of materia medica on the human