 Hi, I'm Peter Adamson, and you're listening to the History of Philosophy podcast, brought to you with the support of the Philosophy Department at King's College London and the LMEU in Munich, online at historyoffilosophy.net. Today's episode, Just Add Salt, Paracelsus and Alchemy. Premodern science does not have the best of reputations. The mere mention of the topic calls to mind the use of leeches and the belief that the sun goes around the earth. So historians of science have had to find ways to explain why we shouldn't just ignore everything that happened before, say, the 17th century. Specialists in premodern medicine might tell you of amazing breakthroughs made long ago. The discovery of the nervous system in Alexandria in the 2nd century BC, or successful eye surgery being done in the Islamic world. They might even suggest that we still have something to learn from long dead scientists. The modern doctor would do well to heed Galen's advice to treat patients holistically, considering their personal history, diet and exercise regime, mental state and individual constitution. While these moves might be persuasive in the case of medicine, they seem less promising when it comes to the disciplines known by the disparaging name of pseudo-sciences applied to such disciplines as astrology and alchemy. Most people assume that both enterprises were a fanciful waste of time, and experts in their history have to work hard to convince even academic colleagues that they are worthy of study. Often they do so by pointing out that we still take astronomy and chemistry seriously, and that these two sciences were intimately bound up with their pseudo-scientific counterparts. When it comes to astrology, it suffices to mention Ptolemy, a near contemporary of Galen's, who was the greatest ancient authority on both astral observation and astrological predictions. As for alchemy, it's surprising to learn how recently it was first distinguished from chemistry. We can find skepticism about the claims of alchemists going back as far as the history of alchemy, specifically as to whether they could really turn base metal into silver and gold. But it was only in the middle of the 17th century that these critics drew a contrast between a spurious art called alchemy, and a genuine science called chemistry. In fact, they are really just the same word. The al at the beginning of alchemy is just the Arabic definite article al at the front of alkimiyya, which was in turn borrowed from the Greek word hemeya. Early modern scholars engaged in some pseudo-science of their own here, offering bogus etymologies including one deriving the syllable al from the Greek word hals, meaning salt. As it happens, salt is going to be a main ingredient of the story I tell in this episode. But before we get to that, we should go beyond etymology to consider that there was good reason for pre-modern scientists to believe in alchemy. While alchemists couldn't actually make gold or silver, they could do a lot of other things. They identified many minerals and chemicals, mastered techniques like distillation, which enabled them to extract pure alcohol, and developed processes for separating metals from one another. That included the isolation of precious from base metals, which could easily be confused with actually producing the precious metal. The same impression could be given by inducing a tincture in a non-precious metal to make it look like gold or silver. Then too, the possibility of alchemy was well-founded in more general theories of nature. For Aristotle and his many followers, all bodily substances were ultimately made from the four elements, air, earth, fire, and water. Aristotle explicitly said that these elements can turn into one another, as when water evaporates to become air. It seems to follow that it should be possible to break down any physical substance, lead for instance into its elemental constituents, and to use these as the basis for making another substance like gold. Here, it's telling that when the Muslim Aristotelian Al-Farabi wrote a short work that is critical of alchemy, he conceded that in principle, anything can be turned into anything. The claims of alchemists are nonetheless false, but only because it is in practice impossible to carry out the transformations they describe. Somewhat earlier than Al-Farabi lived Jaber ibn Hayyan, whose name came to be attached to a large corpus of alchemical writings that would become influential in Latin translation. These writings drew on the ideas of Aristotelian physics, including the four element theory, but Islamic alchemy could also be based on alternative ideas about material constitution. In my own recent book on the doctor, philosopher, and alchemist Abu Bakr al-Razi, I've suggested that he grounded alchemy in an atomic theory of matter. New substances could be produced by dissolving composite bodies and recombining their particles. Supposedly, al-Razi used this technique to produce an elixir for transforming metals. He once outdid a rival alchemist who turned metal into silver by using such an elixir to turn that silver into gold. As this story reveals, the goal of alchemy was not necessarily to start with one substance and melt, dissolve, or fuse it to make it into something else. Rather, alchemists often spoke of producing a chemical substance, the famous philosopher's stone, which could then be applied to suitably prepared metals to transform them as desired. You might remember that Cornelius Agrippa talked about the philosopher's stone as perfectly balanced. This echoed long-standing alchemical theories. According to one idea, the stone was a mixture of pure elemental fire and water, which were in this context called sulfur and mercury, or designated by nicknames like Mars and Vulcan to avoid revealing trade secrets. Often an analogy was drawn to medicine. The philosopher's stone was like a drug being used to treat metal by eliminating impurities or releasing their inner spirit. Like many pre-modern doctors, going back as far as Galen, alchemists paid attention to the influence of the stars on their procedures. In both medicine and alchemy, the same technique that works on one day may fail on another due to a different astral configuration. This brings us to the most famous figure of Renaissance alchemy, Paracelsus, whose central achievement was to adapt chemical ideas for use in medicine. Fittingly enough, Paracelsus is itself a nickname, and rather unnecessarily so since he already sported the rather magnificent appellation Theophrastus Bombastus von Hohenheim. Bombastus looks like it must be a literary conceit, but it really was his family name. Still, it fits nicely because Paracelsus was quite a bombastic individual. He was a widely traveled man who wore a sword while sleeping and could defeat peasants in drinking contests. His enormous body of writings is full of invective against rivals and critics, and against traditional authorities in philosophy and medicine. Born originally in the Swiss town of Einsiln, Paracelsus applied his trade in many cities, including Bern, where in 1527 he outraged the university masters with his unorthodox ideas and his insistence on teaching in German from his own writings instead of lecturing in Latin from a standard curriculum. Perhaps no quotation sums him up better than this one, my shoelaces know more than you and all your schoolmasters, Galen and Avicenna, and all your institutions of higher learning. The reason Paracelsus attacked Galen and Avicenna is that these were the two central medical authorities of his day. Supposedly, he even publicly burnt a copy of Avicenna's medical treatise The Canon. As this begins to suggest, he was centrally interested in medicine. Scholars have even sometimes suggested that he had no interest at all in the practical transformation of metals, but this seems to be false. He refers in several texts to his own success in increasing the weight of gold in a mixture while separating it from other metals, and he plausibly describes how he turned iron into copper, or rather apparently did so. He would have been able to produce a replacement reaction whereby iron replaces the copper in copper sulfate, allowing him to get pure copper as a byproduct. Still, he mostly presented himself as an expert in the use of alchemical procedures to treat the human body. His works launched a movement of Paracelsan medicine that swept across Europe, helped along by stories of apparently miraculous cures performed by him or achieved by using his methods. This constituted a novel approach to medicine. In the Galenic tradition, to which Avicenna belonged, treatments were based around the idea that the body is made up of four humours that need to be kept in, or restored to, proper balance. The humours blood, phlegm, black bile, and yellow bile shared their properties with the four Aristotelian elements. So this kind of medicine was, like medieval alchemy, based on a physical theory that was standard orthodoxy among Aristotelian schoolmen at the universities. Paracelsus saw things very differently. While he accepted the reality of earth, air, fire, and water, for him these were not fundamental principles. Instead, he spoke of three firsts, namely sulphur, mercury, and salt. Here, salt has been added to the pair familiar from earlier alchemical writings, sulphur and mercury. They are powerfully influenced by the stars, and in turn give rise to diseases, an explanation that Paracelsus finds far more plausible than those offered by Galenic medicine. How, for example, can we explain the outbreak of a plague? Surely it isn't that many of the people in a given city suddenly have the same humoral imbalance. Instead, an astral configuration is causing a build-up, or tartar, of mercury in their bodies, yielding such symptoms as boils on the skin. In general, he says, diseases grow in the human as grass and shrubs do from the earth. It isn't only the human body whose properties are determined by the three firsts. They are the ultimate constituents of all bodies, hidden under the outer form or aspect of things. They are the real prime matter, spoken of, but not properly understood, by Aristotelians. We can see them at work in such everyday processes as the burning of wood, which yields flame, smoke, and ash, the manifestations of sulphur, mercury, and salt, respectively. Strictly speaking, each kind of substance has its own version of sulphur, mercury, and salt. They are not just universally present material stuffs. Rather, they are understood in functional terms. It is salt that gives bodies their solidity, sulphur their combustibility, and mercury their fluidity. Paracelsus compares the three principles to seeds jumbled in a sac, whose fruits emerge through natural and artificial processes of material transformation. His natural philosophy, thus, applies an organic metaphor, even to supposedly dead matter. A nice illustration is his account of the generation of minerals, which for him grow out of elemental water as the seeds of salt, sulphur, and mercury cause it to form into a viscous fluid that sprouts through the earth like roots in soil. Likewise, earth is an elemental mother full of seeds, which blossom forth as vegetation and animals. God placed the seeds of all things in the elements from the beginning of creation, with different fruits coming forth at different moments, which are predestined for them, as most clearly illustrated by the seasons. As he nicely puts it, everything has its own harvest, its own autumn, at its own time. Paracelsus calls this process natural alchemy. As for human alchemists, they must of course take their cue from this bold physical theory. Paracelsus is scornful of previous scientists who, in his opinion, made discoveries by happenstance depending on more or less random experiences rather than theory. Ironically, this is a critique that his favorite target, Galen, had leveled at some of his own predecessors, especially those in the so-called empiricist school. With a theory of seeds in hand, the alchemical doctor might treat an illness like dropsy as follows. First, recognize its cause, namely a buildup of salt in the body. Then, fight this by applying mercury, which Paracelsus rather alarmingly sees as a very useful drug. Though he admits that it sometimes causes harm, this happens only when it is administered at the wrong time, that is, under the wrong astral influence. One might also use mercury to cure a mercury-based disease, purifying or rectifying its influence in the body, an early example of the homeopathic principle in medicine. Paracelsus thus transposes to the medical context an idea that was fundamental in the history of alchemy, namely that the adept of this art should perfect nature. Showing again his penchant for homely comparisons, he says that the alchemist's work is really no different from that of the baker or winemaker. Where an Aristotelian or Galenic scientist would assume that perfecting nature means establishing a correct balance between the constituents of a body, Paracelsus's idea is the reverse. Thinking alchemically means separating out the fundamental bodily principles and making them as pure as possible. He draws an analogy to the stomach, in which digestion removes what is poisonous and excretes it, while the pure nutriment is retained. Likewise, the alchemist is trying to isolate and then use whatever is most fundamental to a substance, for example, to produce a drug. Across his career, Paracelsus uses different terminology for this underlying principle. It is the predestined element, the hidden power, the soul or spirit in the bodily mixture. It may not have escaped you that these ideas have obvious echoes with Christian religion. The trinity of chemical principles is a pretty obvious echo of the three divine persons. In fact, before Paracelsus, an early 15th century treatise called the Book of the Holy Trinity had proposed adding salt to mercury and sulfur to get three physical principles. The spirit, hidden within the bodily substance, an immaterial essence placed within it by God, may also remind us of the Incarnation. More explicitly, Paracelsus says that all natural things are signs of God. Can we go further here and link his reformation of alchemy and medicine to the religious reformation going on around him? After all, he was putting forth unorthodox ideas just as Luther was doing the same thing, especially in the 1520s. Furthermore, his attacks on medical authority and his claims of independence, once he bragged that he had not read a book for 10 years, obviously parallel Luther's scornful rejection of scholasticism. Paracelsus's opponents in Basu even called him the Luther of medicine, intended as a term of abuse, but repeated by later Paracelsus with pride. So it makes sense that, though he did not himself leave the Catholic faith, his ideas flourished especially among Protestants. Adam of Bodenstein, who adopted Paracelsus's methods after they cured him from an illness, went on to publish many of the master's works and promote his teachings in Basu. And who was Adam of Bodenstein's father? None other than Andreas von Karlstadt, the reformer who was too radical to stay in Luther's Wittenberg. At the very least, these connections show that Paracelsus's science was a product of its age, but he can be more directly compared to figures like Agrippa and Trithamius, who, as we saw, helped to inspire Agrippa's interest in magic and may also have had a hand in the formation of the young Paracelsus. We should certainly not conflate or confuse alchemy with magic, but the two arts do share a number of things. Both magicians and alchemists tended to cloak their teachings in secret, as with the aforementioned use of code names or simple refusal to spell out procedures fully, lest the uninitiated become acquainted with them. We can find that in Paracelsus, too, who once refused to explain openly how to make precious metals, saying, it is better to remain silent and let the poor stay poor. More fundamentally, the two arts both drew on a pool of common inspirations. We've already talked about the importance of astrology, and can add to this the Jewish mystical tradition of Kabbalah. Paracelsus once said, if you do not understand the use of the Kabbalists and of the old astronomers, you are not created to open your mouth about the alchemical art. This aspect of his writings has not always enthused modern-day scholars. One of them comments that Paracelsus as a philosopher and alchemist may sometimes resemble a Kabbalistic scholar more than a laboratory researcher or natural scientist in the modern sense. But at the time, it was, like salt, very much to some people's taste. A leading example here would be Heinrich Kunrath, who used Kabbalistic techniques like numerology and the analysis of words to expound Paracelsan alchemy. Take for instance the central word elixir, spelled by Kunrath, E-L-I-X-E-I-R. According to Kunrath, the first two letters, E-I, represent the Hebrew word for strong. The following I and X are the Roman numerals, one and ten. And the last three letters, E-I-R, are the Greek word for air. While this may seem pretty far from the concerns of Luther and Calvin, Peter Forshaw has pointed out that Kabbalah was supposed to go back to Moses and the foundations of Jewish religion, so it could be seen as more fitting for Christian scientists than the work of pagans like Aristotle and Galen. Kunrath was only one of many scholars who worked within the new Paracelsan paradigm. Another was Peter Severinus, who was physician to Frederick II in Denmark and wrote a synthesis of Paracelsan medicine. Severinus was faithful to Paracelsus's irreverent attitude as well as his medical theories. We do not, he said, owe the Greeks nor Arabs any respectful consideration. We are the servants of the sick. As we'll be seeing later, there was considerable support for Paracelsan philosophy in France, where it was especially the Protestant Huguenots who adopted it. Over in England, the alchemist John Dee was acquainted with the Paracelsan movement, and believe it or not, a work written in Aleppo in about 1640 by Salih ibn Salum showed knowledge of Paracelsus's ideas, meaning that his influence was even felt in the Ottoman Empire. Yet these ideas left many others with a bitter taste in their mouths. In Basel, opposition to Paracelsan theories remained strong. Here, a student named Thomas Moffat was forced to remove all trace of them from his writings before he could be granted a degree. One of the staunchest opponents was Andreas Libavius, who believed that one could produce gold alchemically, but using the old-fashioned methods of medieval alchemy. Libavius thus polemicized against the Paracelsans and in favor of the natural philosophy of Aristotle and the medical treatments recommended by Galen. Another critic was Thomas Erastus, a professor of medicine at Heidelberg. In a set of Disputations from 1572, he rejected the idea that one could chemically transform one type of substance into another, and then back again. Such cyclical change is possible, but only between the four fundamental elements, air, earth, fire, and water. He worried that Paracelsus's chemistry made ordinary substances like plants, animals, and humans out to be nothing but aggregates or mixtures of more basic ingredients, which would undermine science itself, since science is the study of the unifying essences of those very substances. Love him or hate him, then, Paracelsus was like many of the chemicals he devoted his life to understanding, bound to provoke a strong reaction. Of course, Paracelsus's detailed proposals about the nature of bodies and the therapies that apply these ideas in medicine have not stood the test of time. Yet his chemical approach to matter and medicine can be said to have survived quite nicely. The mere fact that students training to be doctors have to study a lot of chemistry would certainly please him mightily. Closer to his own day, his works contributed to a broader development in the 16th century. As Aristotelianism came under attack, new ideas started to sprout up in a whole range of scientific fields. Most famously, and as we'll be discussing soon, this happened with astronomy. But it also happened with a topic that was, quite literally, more down to earth, the material basis of the bodies around us. That will be our topic next time, as we continue to pursue the idea that the natures of things are seeded in their material constituents, along with other theories about the composition of bodies. So don't think for a moment that it doesn't matter whether or not you join me for the next episode of The History of Philosophy, without any gaps.