Meteorology and Alchemy
Meteorology and Alchemy
Meteorology. Although meteorology is now considered a subdivision of the earth sciences, to medieval scientists it was inextricably intertwined with the study of optics. Once again, the connection lies in the Aristotelian view of the world, for in his system both meteorology and optics take place in the sublunary region above the earth. Their natural place was within the spheres of air and fire, which lie above those of earth and water. Thus, the study of rainbows fell under both meteorology and optics, as did investigations of comets, shooting stars, the aurora borealis, and optical “illusions” such as the apparent change in the size of the Moon when it is at the horizon and the change in color of the Sun at dawn and dusk. The medieval scholars Albertus Magnus, Roger Bacon, Witelo, and Theodoric of Freiberg were the first to realize that rainbows were caused by the reflection and refraction of light from individual drops of water in the atmosphere—an advance on the explanation offered by Aristotle, who said rainbows were the result of light rays passing through clouds.
Weather Signs. Meteorology was also intimately tied to the broader field of signs, which also included astrology. Meteorological events such as eclipses, thunderheads, fog, and comets were said to be signs of impending famine, fortune, or failure, but students of meteorology were also concerned about predicting the weather. Although it may seem strange today, medieval weather prediction on the basis of how far the sound of bells carries—part of a seven-year-long investigation in fourteenth-century England—does in fact have validity. Although the scientists who carried out this investigation did not articulate their findings in the same way as a modern meteorologist would, it is true that the distance sound travels is correlated to humidity—that is, the more moisture in the air, the farther sound travels—and is a strong indicator of weather patterns. Since the cornerstone of medieval society was agriculture, the study of weather was important, and—even when interpretations of weather signs were irrelevant—the search for practical meteorological knowledge focused the medieval mind on the concept of cause and effect in the natural world, one of the cornerstones of modern scientific method.
Alchemy. Perhaps the best-known attempt of medieval scientists to discover the underlying principles of the natural world was alchemy. Alchemists sought the deep connections between matter and qualities and heaven and earth, in order to control them. Modern people misunderstand alchemists as irrational magicians trying vainly to turn lead into gold, but they were acting rationally within the medieval belief system. Furthermore, though they failed to transmute lead into gold, they succeeded at teasing apart the threads of the fabric of nature to produce pure forms of elements (in the modern sense of the word) and developed sophisticated laboratory equipment and procedures that were important contributions to later scientific attempts at understanding the natural world.
Non-Aristotelian Roots. Alchemy began in the ancient world and seems to have reappeared when many ancient Greek writings were circulated in the twelfth century. One feature sets alchemy apart from the rest of medieval science: it is not based on Aristotelian doctrine and was thus never studied in the medieval universities. Instead, alchemy is based on mystic ideas from the Near East and India as well as many of the Platonic ideals that Aristotle rejected or modified. Thus, although the Aristotelian theory of the four qualities—hot, cold, moist, and dry—plays a large role in alchemical rationale, as alchemists sought out the connections in the natural world, their explanations differed from those of the Scholastics, or “Schoolmen” (as Aristotelian scholars were called), and hence kept their two worlds apart.
Connecting the Celestial and Terrestrial Realms. While the Scholastics held with Aristotle (and Christianity) that the celestial and terrestrial realms were fundamentally different, alchemists believed that they were connected. The
motions of the planets interested alchemists, who needed to be well versed in astrology, and, they thought, each planet signifies and controls a primary metal on earth. In alchemical theory the moon controls silver and the sun, gold; Jupiter is linked with tin and Saturn with lead; while Mars controls iron, Venus controls copper, and Mercury, of course, governs mercury. The results of mixing metals were determined not only by the properties of those metals but also by when the experiment was done; that is, where the planets were at the time of the mixture.
The Materia Prima. Alchemists sought control over nature. They hoped to discover a “Philosopher’s Stone” that could bring about the transmutation of base substances into fine substances and an “Elixir of Life” that could prolong and even create life. These concepts were based on the Neoplatonic idea that there was some fundamental matter, or materia prima (literally, first matter) in nature that was responsible for all change. Linking this idea to the concept of the four qualities, the alchemists attempted to mix substances with either complementary qualities that would reinforce one another or contradictory qualities that would cancel out one another to produce a final substance with the desired balance of hot-cold and wet-dry. Although alchemists worked from these seemingly odd principles, their experiments had some practical results. To perform their experiments they had to produce pure forms of the substances they wanted to combine, and in so doing they advanced medieval knowledge of distillation, smelting, amalgamation, precipitation, and other chemical processes. At the same time they developed many techniques and pieces of apparatus that were the cornerstone of the modern chemical innovations.
Carl B. Boyer, The Rainbow from Myth to Mathematics (New York: Yoseloff, 1959).
Lorraine Daston and Katherine Park, Wonders and the Order of Nature, 1150–1750 (New York: Zone Books, 1998).
Pearl Kibre, Studies in Medieval Science: Alchemy, Astrology, Mathematics, and Medicine (London: Hambledon Press, 1984).
David C. Lindberg, Theories of Vision from al-Kindi to Kepler (Chicago: University of Chicago Press, 1976).