“Why did they think they could turn base metals to gold?” “How could they possibly believe mermaids and unicorns were real?” “What numbskull thought a whale was a fish?” As a historian of science, I’ve been asked some version of this question often by students or general readers—especially if they work in the sciences. The not-so-subtle subtext: “Could they really have been this dumb? Thank goodness we know better.”
The reality is that incredibly smart, educated, even prominent people believed in all of the things above. Isaac Newton would die an alchemist. Johannes Kepler, the astronomer and mathematician for whom a fancy NASA telescope is named, practiced astrology, which was part of the curriculum in European universities well into the seventeenth century. Historians of science seek to understand bygone worldviews in their full complexity, however strange, sometimes laughable, or downright reprehensible those might be. This is not just an exercise in empathy or honoring the past in its rich pastness. It’s a vital tool for seeing modern science as part of—not liberated from—a still-unfolding story.
“On the Philosopher’s Stone in a Brief Essay,” bound within the Musaeum Hermeticum Reformatum et Amplificatum, a 1678 compilation of earlier alchemical texts that Isaac Newton held in his own library. Public domain.
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An opossum in Dutch collector Albertus Seba’s so-called Thesaurus, an illustrated natural history. The opossum’s pouch reveals its—ahem—qualities which would help inspire Linnaeus to create the category Mammalia. Public domain.
Take the taxonomist Carl Linnaeus, a name any modern biologist knows well. We still use Linnaeus’s binomial system (which he did not invent, but rather systematized and popularized) to put words—like his very own Felis catus, or the slightly more colorful Crikey steveirwini for a snail named in 2009—to our maddeningly diverse natural world. Linnaeus ran counter to many of his contemporaries by insisting creatures like whales and dolphins were quite different from fish, despite their similar shape, fins, and watery abodes. (Don’t even get me started on fish systematics.)1 He grouped them, along with cats and humans and other hairy nippled things, under Mammalia—a term that had everything to do with breasts, racism, and wet nursing, as shown by historian of science Londa Schiebinger.2 But the idea that whales were anything but fish remained controversial and counterintuitive, even into the nineteenth century.3
Comparative illustration of cetacean and human digits in Robert Hamilton’s The Natural History of the Ordinary Cetacea, or Whales (1837). Public domain.
Diagram of plant classification by botanical artist Georg Dionysius Ehret, 1736, that would be included in Linnaeus’s Systema Naturae. Public domain.
On the other hand, Linnaeus also had many ideas that wouldn’t pass scientific muster today. Some were quirky: he had a bona fide mermaid research agenda and described plants as having nuptials and marriage beds. Some were deadly serious: he devised a racial classification of humanity which, although based around the influence of climate rather than innate characters, still framed Europeans as superior.
Sometimes science “progresses” in terrible ways. Practices like racial science and eugenics often get dismissed as pseudoscience. But they were viewed as legitimate lines of biological inquiry in their time—with ties to seats of scientific power like Harvard University, the American Museum of Natural History, and the American Association for the Advancement of Science (which publishes the journal Science).4
Brushing off these practices as unscientific implies that “true” science is, and always has been, unimpeachable. It denies us a chance to examine what flaws may fuel our own ways of thinking. And it absolves us from reckoning with the wreckage of the scientific past. To name just one example, the remains of many people who unwillingly gave their lives (and afterlives) to racial science still languish in major museum collections. The recent battle over the bones of the MOVE bombing victims—child victims—illustrates all too well that this history is alive, that modern scientists inherit it, and that turning a blind eye to science’s potential for harm tends to harm marginalized people the most.
Knowledge doesn’t advance in an inevitable upward trajectory. Time doesn’t guarantee we know—or act—better than before. Sometimes we step back or lose knowledge. Sometimes we find out centuries later that the silly people of the past were onto something all along. In 2025, for instance, physicists at CERN’s Large Hadron Collider turned lead, very briefly, into gold. “Newton,” wrote the economist John Maynard Keynes, “was not the first of the age of reason. He was the last of the magicians.”5 Perhaps he was both.
The Large Hadron Collider at the European Organization for Nuclear Research (CERN). In 2025, CERN’s Large Hadron Collider transmuted lead into gold Credit: Maximilien Brice/CERN, CC BY-SA 3.0.
In my class on the history of science, students complete two primary source exercises—one at the beginning of term, and one at the end. For the first, they must find a pre-1800 article in the Philosophical Transactions of London’s Royal Society, the first-ever scientific journal in the English-speaking world. For the second, they pick a scientific journal article from the last few decades and submit it to the same critical analysis—treating it not as scientific truth, but merely another historical document. What voices are present in the text? What problem is being solved or hypothesis tested, and why does that matter in cultural context? What kinds of evidence are viewed as admissible? Who funded the work? How do the authors use images to make their case, and why? What invisible technicians—squirreled away in the acknowledgments, or deduced from a throwaway line—made the research possible? These sorts of questions can be asked not only of whimsical seventeenth-century texts like Robert Boyle’s treatise on shining meat. My students have brought the historian’s eye to papers on stem cells, macrophages, organocatalysis, and the neurobiology of birdsong.
Read as primary sources, recent publications show twenty-first-century science to be part of a long tradition of inquiry, not separate from it. After all, the Philosophical Transactions are still in print.
- Carol Kaesuk Yoon, Naming Nature: The Clash Between Instinct and Science (New York: W.W. Norton & Company, 2009), 257.
- Londa Schiebinger, “Why Mammals are Called Mammals: Gender Politics in Eighteenth-Century Natural History,” The American Historical Review 98, no. 2 (1993): 382–411.
- D. Graham Burnett, Trying Leviathan: The Nineteenth-Century New York Court Case That Put the Whale on Trial and Challenged the Order of Nature (Princeton: Princeton University Press, 2007). Although this short piece focuses on a narrower definition of science, there is an important body of scholarship (and many more essays yet to be written) on vernacular science, folk taxonomy, Indigenous epistemologies, and the history of knowledge more broadly. For one overview, see Lorraine Daston, “The History of Science and the History of Knowledge,” KNOW: A Journal on the Formation of Knowledge 1, no. 1 (Spring 2017): 131–154.
- See especially Donna Haraway, “Teddy Bear Patriarchy: Taxidermy in the Garden of Eden, New York City, 1908–1936,” Social Text 11 (Winter 1984–1985): 20–64. On the deeper history of eugenics, see Mackenzie Cooley, The Perfection of Nature: Animals, Breeding, and Race in the Renaissance (Chicago: University of Chicago Press, 2022).
- Quoted in William R. Newman, Newton the Alchemist: Science, Enigma, and the Quest for Nature’s “Secret Fire” (Princeton: Princeton University Press, 2019), 3.
