PROBABLY THE LAST ACADEMIC ORATION ABOUT ALCHEMY given in the Netherlands took place at Leiden in December 1737. The speaker was the physician Abraham Kaau, and he entitled his address “On the Joys of the Alchemists.”1 While the title might seem to promise a positive portrayal of alchemy, Kaau's oration was in fact a mocking account of the ancient art, and one can imagine his audience's laughter at alchemy's expense. By 1737, in the Netherlands at least, alchemy had no serious public defenders. The subject had become emblematic of foolishness, a relic of the past, a source of amusing entertainment (as Kaau used it), or an example of what chemistry was not. In 1737, chemistry was a serious academic discipline and an increasingly important commercial practice, and in Kaau's mind alchemy had very little connection with it.

This was not the case just twenty years earlier. In September 1718, an earlier generation of Leiden professors had gathered to hear the inaugural oratie of their newly appointed professor of chemistry. This new chemistry professor was, ironically enough, Abraham Kaau's uncle and a much more famous person—Herman Boerhaave. In 1718, the transmutation of metals into gold remained a serious topic of study for many and one of the enterprises that most readily characterized chemistry for the general public. Boerhaave did not mock chemistry's past, but he did find it necessary to apologize for it. Entitled “Chemistry Purging Itself of Its Errors,” his oration defended chemistry from critics. “I must talk about chemistry!” Boerhaave lamented. “About chemistry! A subject disagreeable, vulgar, laborious, far from the affairs of intelligent people, and ignored or considered suspect by the learned … a discipline fruitful of errors, the poorest in good fruit, the progenitor of poverty, the bankruptor of wealth, the destruction and ruin of common sense.”2

Boerhaave was both embarrassed by and proud of chemistry. “We are horrified and embarrassed by the silly nonsense into which the crowd of chemists plunges with sinful trespass. What fables, superstititions, and fancies! Hardly anywhere can more raving madness be found.” His words are understandable only when we recognize that many in his audience did not see a clear distinction between what we call alchemy and chemistry. The search for metallic transmutation—what we call “alchemy” but that is more accurately termed “chrysopoeia”—was ordinarily viewed in the late seventeenth century as synonymous with or as a subset of chemistry. This terminological issue is why William Newman and I suggested using the archaically spelled “chymistry” to refer to the entire subject before its separation into alchemy and chemistry in the early eighteenth century.3 Many chymists pursued chrysopoeia as part of their activities, and in doing so they employed the same techniques, instruments, and guiding principles as in the rest of their work. All their chymical activities were unified by a common focus on the analysis, synthesis, transformation, and production of material substances. The sundering of chrysopoeia from chymistry was under way when Boerhaave spoke in 1718, and he is among those who promoted it, explaining that the new chemists of his day—like himself—were busy making their subject respectable and that his colleagues had nothing to fear from this questionable subject.

The banishment of chrysopoeia—increasingly called “alchemy” in the early eighteenth century—from respectable chemistry remains a topic of study. Yet it is clear that developments in the understanding of nature had little to do with it. No new theories or experiments sounded the death knell for chrysopoeia, and the arguments used against it in the 1720s were the same as those used routinely and ineffectively since the Middle Ages. Early eighteenth-century antialchemical rhetoric, however, laid new emphasis on fraudulent practices. It was spokesmen for scientific societies and institutions—like Bernard de Fontenelle and Étienne-François Geoffroy at the Académie Royale des Sciences and Boerhaave at Leiden—where chemistry was struggling to take on a new identity in terms of professionalization and social legitimacy, who led the charge. They cast alchemy as an intellectual taboo, its practitioners as socially unacceptable and disruptive, and its content and practice as something other than the chemistry they represented. This campaign was so successful that chrysopoeia disappeared from respectable circles within a generation (although some of the most prominent eighteenth-century chemists who rejected it publicly continued to pursue it privately).4

Subsequent developments made alchemy's original unity with chemistry—or other scientific practices—seem increasingly implausible. Late eighteenth-century Germany saw a resurgence of alchemy, but within secret societies. The late nineteenth century witnessed a broader revival of alchemy, but within the context of Victorian occultism. These Victorian occultists reinterpreted alchemy as a spiritual practice, involving the self-transformation of the practitioner and only incidentally or not at all the transformation of laboratory substances. Early twentieth-century psychoanalysts reexpressed this occultist interpretation in clinical terms and claimed that alchemical texts actually described psychological processes and archetypal images. These latter-day interpretations became standard “explanations” of historical alchemy, such that with every passing generation alchemy became more and more distanced from chemistry and from scientific thought in general.5 Thus, when the history of science emerged as a professional discipline, alchemy seemed far from anything scientific. The positivist outlooks of the day recapitulated Enlightenment polemics, and early historians of science presented alchemy as not simply nonscientific, but antiscientific—an obstacle to progress. George Sarton penned an extended rant against the “extraordinary muddle” of alchemy and labeled alchemists as all “fools or knaves, or more often a combination of both in various proportions.” In 1952 Herbert Butterfield famously wrote that modern scholars who study alchemy end up “tinctured by the same sort of lunacy they set out to describe.”6 (Did he have particular contemporaries in mind?) Alchemy's separation from the history of science thus continued to deepen for over two centuries.

Remarkably, the speed of alchemy's rehabilitation today rivals that of its eighteenth-century demise. Historians of science are now paying unprecedented attention to alchemy, and other academic fields are likewise acknowledging its wide influence and cultural relevance. Has the entire discipline of the history of science become tinctured by lunacy? A brief retrospective on alchemy's rehabilitation—and the opposition to its revival—highlights developments in both our discipline and our wider understanding of science.

Several steps paved the way for alchemy's “revival.” The careful researches of Julius Ruska, Paul Kraus, and others addressed long-standing biobibliographical problems. Walter Pagel and Allen Debus championed the importance of iatrochemistry, especially in the cases of Paracelsus, Van Helmont, and their followers. Few scholars, however, dared approach European chrysopoeia seriously. Among those who did, Frank Sherwood Taylor, founding editor of Ambix, should be singled out. He wrote his 1952 The Alchemists with great historical sensitivity, insight, and modesty, endeavoring to understand alchemists on their own terms at a time when most others relied on superficial or programmatic assessments. Such foundational work did not, unfortunately, penetrate far into the field.

Another key step was the revelation that canonical figures of the Scientific Revolution pursued chrysopoeia seriously. This development threw steadfast believers in Enlightenment or positivist rhetoric on the horns of a dilemma—either alchemy was more rational than they believed or their heroes were less so. Newton's alchemy would not have become a cause célèbre of the 1970s and 1980s had eighteenth-century and subsequent generations not recrafted Newton into the very model of the modern scientist and presented alchemy as something removed from—indeed, opposed to—science. Nor would Newton's alchemy have been kept hidden for so long as an embarrassment. The nineteenth-century biographer David Brewster recoiled at Newton's voluminous notes on “the most contemptible alchemical poetry” and his study of texts that were “the obvious product of a fool and a knave.”7 The commission that examined Newton's manuscripts for Cambridge University concluded that the alchemical materials were “of very little interest” and his theological work not “of any great value.” These “unimportant” materials were returned to their owner and eventually bundled up into lots for the infamous Sotheby's auction of 1936.8 Study of the alchemical papers gathered by John Maynard Keynes and given to Cambridge in 1946 was sporadic at first and sometimes took the form of sifting nuggets of “positive chemistry” from “mystic alchemy” using anachronistic or programmatic criteria—the latter explained away or more often simply ignored.9 But thanks to persistent scholars like R. S. Westfall and B. J. T. Dobbs—despite the then-meager understanding of alchemy they had to draw on and the criticism they received from more hidebound historians—it is now common knowledge that Sir Isaac Newton's alchemy occupied him as seriously as optics or mathematics, just as his theological pursuits rivaled his physics in terms of the time and energy he spent on them.10

Robert Boyle received similar treatment. The image crafted for him was that of a “Father of Modern Chemistry” who cleared the way for modernity by sweeping away misguided alchemy. When biographers examined Boyle's papers in the 1740s, they discarded many alchemical materials as worthless. Given the disrepute attached to alchemy by that time, it was not something they wanted to have connected to their hero. Ironically, much of this material—such as the work on transmutational processes Boyle called his “Hermetick Legacy”—had already been pilfered shortly after his death in 1691, but then probably on account of its perceived value. The surviving material documents unambiguously Boyle's lifelong chrysopoetic activities, his search for the philosophers' stone, and his attempts to contact adepti.11 Once again, some authors (but not all) endeavored to ignore or explain away Boyle's alchemy, simultaneously elevating his 1661 Sceptical Chymist into an “epoch-making book,” “a death warrant” that “struck at the root” of alchemy (it wasn't and it didn't).12 As with Newton, revealing Boyle's alchemy was sometimes met with resistance or even outrage—I recall being yelled at during an international conference in the 1990s for “defaming” Boyle and more recently have had my claims about Boyle and alchemy attributed to the use of hallucinatory drugs.

Current scholarship now removes any grounds for surprise (or horror) over the likes of Boyle or Newton studying alchemy. Further research continues to add to the roster of well-known figures who seriously pursued chrysopoeia. Now that we recognize alchemy as part of natural philosophy, we should instead be surprised if early modern thinkers interested in the constitution and manipulation of matter had not studied or pursued chrysopoeia. Hand-in-hand with historiographical developments beyond earlier “great men” narratives, historians of science are revealing how ubiquitous chymical practice—including chrysopoetic endeavors—really was. Alchemy extends from well-known figures to a host of lesser-known characters in and out of academic, medical, courtly, and private settings and across the whole social and intellectual spectrum of projectors, entrepreneurs, refiners, miners, and others, all the way to brewers, shoemakers, and drapers.13 Indeed, one of the most important features of the new historiography of alchemy is the recovery of its diversity and dynamism.14 Part of the rhetorical strategy of the eighteenth century, and of debunkers of alchemy ever since, was to lump all chrysopoeians together, enabling the criticism (or parody) of a part to be extended to the whole. In 1722, for example, Geoffroy cited the most celebrated instances of transmutational fraud and allowed them to be extrapolated to the whole of chrysopoeia. Subsequent writers routinely picked marginal figures or ideas as representative of the whole or lumped excised snippets from authors widely separated in time and cultural context together into an undifferentiated pastiche. Interestingly, authors from opposite ends of the spectrum—positivists and occultists—converged on this point. For the former, alchemy was distinguished from progressive science by being static, an unchanging body of inherited ideas based on a priori reasonings and unresponsive to observations. The latter, encouraged by the notion of continuity promoted by “ancient wisdom” narratives prominent in esoteric circles, crafted all-embracing, transtemporal definitions of alchemy. Both viewpoints have been raised even recently in objection against the new historiography of alchemy.15 Certainly, some chrysopoetic authors facilitated such treatment by rhetorically claiming a unity to the alchemical quest (“all the sages say one thing”) and by reinterpreting earlier authors to support their own ideas, thereby creating a superficial impression of uniformity.

But careful contextual readings of alchemical texts now continue to reveal that alchemy was never monolithic or static. Early modern European alchemy alone displays a staggering diversity of theories, practices, and purposes: Scholastic and anti-Aristotelian, Paracelsian and anti-Paracelsian, Hermetic, Neoplatonic, mechanistic, vitalistic, and more—plus virtually every combination and compromise thereof. Arguments flourished over the starting material(s) for the philosophers' stone, just as diverse theories drawing on substantial forms, semina, particles, principles (one, two, three, four, or five—depending on the author), and other concepts abounded to explain its transmutational abilities and the nature of chymical change. Experimental results and observations fed into both theory and practice. Notwithstanding the caricature of alchemists “single-mindedly” seeking the philosophers' stone, legions of hopeful chrysopoeians in fact collected, traded, and experimented with a myriad of processes for less potent transmuting agents known as “particulars,” and most practitioners diversified their activities—for practical economic reasons, if nothing else—to include pharmaceutical and commercial production. Such diversity renders it impossible to make blanket statements about the content and influence of alchemy without careful qualification and guarantees that we will have much to learn about alchemy for many years to come.

Another key step toward resituating alchemy in the history of science required getting a handle on what alchemists actually did every day. The enigmatic character of alchemical texts seemed to defy understanding. Rhetorically motivated parodies from the eighteenth century or misguided interpretations from the nineteenth and twentieth filled the resultant vacuum, providing a consensus that, whatever alchemists did, it was neither chemistry nor scientific and in some cases was not even related to the material world. Of course, many scholars did enumerate specific contributions from alchemy, often by identifying the earliest appearance of some substance or technique.16 Such endeavors were valuable but could do little to rehabilitate alchemy as part of the history of science, both because these isolated “firsts” fit easily with the notion that alchemists stumbled on things more or less by accident and because the extraction of such positive nuggets left the bulk and fabric of alchemical writings, theories, and practices, especially chrysopoetic ones, unexplained.

Thus it was necessary to show that apparently incomprehensible, seemingly fanciful, or metaphorically expressed texts actually rested on practical chemical foundations. The desire to know what alchemists actually did in practice led me—initially back in the early 1980s—to try to replicate their results, to see what they saw (and often enough smell what they smelled, although I continue to draw the line at tasting what they tasted). Eventually, many processes that seemed implausible were found to work once impurities present in early modern starting materials were taken into account. Boyle's transmutation of gold into silver worked exactly as he described, even if his “silver” turned out to be silvery antimony. Even some of the most bizarre alchemical imagery supposedly hiding routes toward the philosophers' stone, once decoded, yielded surprising and workable processes that must have required astonishingly well-developed experimental techniques.17 Interestingly, just as the revelation of Boyle's and Newton's alchemical endeavors did not always find a warm welcome, neither did these results or the very technique of replicating experiments—by either die-hard alchemical skeptics or exponents of the then-prominent sociological schools. It is particularly encouraging, therefore, to witness the recent interest in historical replications, not just in alchemy but across the history of science, as a tool for increasing our historical understanding. Together with fresh understanding of the theoretical systems chrysopoeians developed, and the clear-minded interplay between theory and practice, these new findings proved that “alchemists” could not be written off as fabricators of imagined processes, mere empirics, or frauds.

While prevailing attitudes toward alchemy (formerly among historians, and still today among much of the general public) required that pioneers in the field emphasize how alchemy was truly part of the history of science—in short, opposing the routine label of “pseudoscience”—it would obviously create an unsatisfactory view of alchemy's richness, character, and context to reduce it to some sort of “protochemistry.” But I know of no modern scholar who maintains that alchemy is part of “science” in the modern sense. The point is that it was fully part of contemporaneous natural philosophy. This important distinction can be too easily obscured by an automatic usage nowadays of “natural philosophy” as a “historiographically correct” substitute term for “science” without adequate reflection on the difference of meaning. Over half a century ago, Walter Pagel, defending the study of topics that positivistic historians of the day saw as “rubbish,” emphasized that early modern thinkers pursued “Philosophia Naturalis,” defined succinctly as “nature in her entirety, cosmology in its widest sense—that is a mixture of Science, Theology, and Metaphysics.”18 In the eyes of earlier generations, the theological, religious, and metaphysical content of alchemical texts disqualified them from being part of the scientific tradition, even while those same eyes “overlooked” similar features in early modern physics, astronomy, or natural history—indeed, in all of early modern “science.” Alchemical texts—like other contemporaneous natural philosophical texts—are implicitly structured on the vision of a tightly interconnected cosmos of God, man, and nature that is full of meaning, purpose, and symbol. In this context chymical transformations frequently and easily carried linkages for their authors with ideas in theology, literature, mythology, and other fields that since the eighteenth century have been considered extraneous. The shift away from such comprehensive perspectives is clear in Boerhaave's oration, for example; as a pedagogical reformer and Calvinist biblical literalist, he was horrified by the metaphorical use of Scripture to support specific laboratory processes and by the linkage of chymical ideas to Christian doctrines. The key role—sometimes explicit, always implicit—of theology and metaphysics in alchemy does not disqualify it as part of the history of science any more than these same features in, for example, Kepler or Newton would disqualify their work.

Indeed, the rehabilitation of alchemy helps broaden our understanding of what is meant by science, its development, and its evolving place in society. Alchemy's exile resulted from a conscious redrawing of the boundaries of “science,” and the modern resistance to assertions of alchemy's importance came from proponents of a narrow view of what counted as science. This view was shaped by eighteenth-century rhetoric and enhanced by nineteenth- and early twentieth-century positivism, progressivism, and a priori or normative philosophical or political formulations about science. Alchemy represented the “other,” a convenient foil against which chemistry or science in general could be set off. Alchemy's estrangement exemplifies how science does not always develop by means of cold reason or demonstrable experiment. Transmutational alchemy, vilified by declamation rather than disproved by demonstration, was ostracized for the sake of professional expedience at a time in which there was no way to know that its goals were physically unobtainable. Chemists of the day had the problem of their social status and reputation to solve, and the public sacrifice of transmutational alchemy was the way they chose to solve it—“cleansing” their field and defining themselves as reputable by marking out a disreputable other. An analogous dynamic explains the antagonism of some twentieth-century historians and scientists toward claims for alchemy's importance and its connection to major figures. They were invested in a particular foundation myth of science. To maintain it, they needed alchemy to be “something other,” something in opposition to which modern, rational, experimental science could define itself and upon which they could in turn define themselves. Hence the intensely personal nature of some of their attacks. There was no place for alchemy in accounts of the canonized heroes of modern science. A similar incredulity or dismissal (and often by the same individuals) sometimes greeted the fact that religion was a crucial motivating force behind the Scientific Revolution and that our heroes from the period were almost invariably committed Christians.19 Over the past fifty years, insistence on the importance of alchemy (and theology) has broadened our discipline's vision and enhanced our understanding of the ever-evolving thing we call science.

Alchemy's exclusion illustrates strategic redefinitions of science, while its rehabilitation points to the contextual nature of those definitions. One gift offered by the history of science is the recognition that science is a far messier process than simple models, wishful thinking, or programmatic philosophies will allow. It collects elements from unexpected sources and synthesizes them in unexpected and unpredictable ways. It is never a mechanical or impersonal process—nor would we want it to be. While the laws of nature exist independently of us, the ways we choose to conceive of them, to explore or not to explore them, to describe or not to describe them—that is to say, science—is a very human affair, filled with all the complexities and simplicities, errors and insights, pettiness and nobility that customarily attend human activity. And, to be sure, alchemy forms an important part of that story.