On Chasing an Enemy That’s Too Small to See

Disease is, in itself, nothing remarkable: It comes with being a multi-cellular organism. Plants sicken and die, and—as farmers and pet owners know all too well—so do animals. What makes humans’ experience with disease different from that of all other species is that we restlessly, continually think about it.

Confronting Contagion is a book about one particular strand of human thinking about disease. It follows the rise, in the West, of the idea that (some) diseases are caused by tiny biological agents that penetrate the bodies of living things. Beginning with the Iliad, the Bible, and the Torah, it traces that idea through the writings of the ancient Greeks and Romans, Medieval “natural philosophers” and Renaissance-era scientists, before arriving at the mid-17th century, when the newly invented microscope revealed a living world too small for the unaided eye to see.

That much of the story—the transformation of “tiny particles” from speculation into observed reality—occupies the first half of the book. The second half traces the working-out, since 1700 or so, of the idea that some of those tiny particles are organisms capable of making living things (plants, animals, us) sick. The midpoint thus sees a marked shift in tone: from the broad, abstract, and conceptual to the narrow, detailed, and practical.

The shift serves author Melvin Santer, an emeritus professor of biology at Haverford College, well. The first half covers its chosen ground competently and comprehensively. All the key figures—ancient Greek philosophers Lucretius and Aristotle, medieval medical authorities Galen and Avicenna, early microscopists Robert Hooke and Antony van Leuwenhoek—are present and accounted for, along with battalions of important, but less-familiar, figures like Marcelo Malpighi. His outlines of their ideas are crisp and concise, if occasionally repetitive, and his connection of the intellectual dots thus laid out is self-assured and convincing, but again, they are the work of an intelligent and well-prepared outsider.

The second half, by contrast, is the work of an expert writing about a subject that, having spent his professional life immersed in it, he knows intimately and understands intuitively. Biological details loom increasingly large in the narrative after 1700, and dominate it after 1800. Organisms, laboratory techniques, and experiments become the building blocks of the story, and Santer explains them, and articulates their significance, with impressive clarity.

Santer’s scientific background also shapes the second half of the book in another, less obvious way. Whether written by professional historians, journalists, or physicians, histories of disease (and scientists’ attempts to understand them) typically focus on the diseases that afflict humans. There are histories of bubonic plague, polio, and influenza, but few histories of diseases that afflict plants and animals, unless—like the blight that triggered the Irish Potato Famine of the mid-1840s—their secondary effects touch human lives.

Confronting Contagion, however, examines humans’ evolving understanding of disease in plants and animals, as well as in themselves. Writing the story this way not only brings out unfamiliar information, but also highlights unexpected connections across three fields that—because physicians rarely compare notes with nurserymen, or pharmacists with farmers—often proceeded in isolation from one another.

Santer has made an important contribution to an under-served field. There are few (if any) other overviews of high-level scientific thinking about the nature of infectious disease penned for the layperson, and Confronting Contagion fills that niche well. The key to appreciating it, however, is to approach it without preconceptions and meet it on its own terms. Readers looking for the broad history of disease promised by the subtitle will be frustrated, and those expecting the highly polished prose familiar from other popular histories of science and technology could be horrified.

Confronting Contagion is a history of scientific ideas. Or rather, of one specific idea: that tiny biological agents, entering the body from outside, can make people sick. It is not, except incidentally, a history of attempts to cure disease, nor is it an examination of how disease (as a concept) has been defined. Given the story that Santer wants to tell, these are reasonable limits. Still, they leave a lot out.

Folk medicine, and other beliefs about disease not rooted in the writings of contemporary theorists, is all but absent. Diseases that are inherited (hemophilia), non-infectious (cancer), or caused by non-biological agents (silicosis) are excluded by definition. Santer steers well clear both of the philosophical issues involved in defining “disease” and of the socio-cultural ramifications of applying the label to (say) alcoholism or removing it from (say) homosexuality. Even without considering the book’s tight focus on the West, Confronting Contagion is not the broad history of “Our Evolving Understanding of Disease” that the cover implies.

A narrow geographical or thematic focus need not, of course, be a flaw in its own right. It can be—and, in Confronting Contagion, doubtless is—a deliberate choice, made in order to limit the size and complexity of the book. The same cannot be said for the pervasive roughness of the presentation. Not every history of science written for general audiences needs to have the polished, reads-like-a-novel narrative style of (say) Steven Johnson’s The Ghost Map (2006).

The prose in Confronting Contagion, however, is artless to the point of ugliness. Its basic prose style suggests equal measures of class notes (the book began as a series of lectures) and block quotations from sources, stirred lightly, and poured the onto the page with no attempt to blend the two together or impose a sense of narrative flow.

Virtually every sentence is understandable, and the paragraphs follow one another in logical order, but there’s no sense of proportion, pacing, or shape. Sections that run for pages butt up against sections that last for two paragraphs. Chapter titles run from the telegraphic (“Chapter 3: Hippocratic Corpus”) to the comically detailed: “Chapter 11: Plant Diseases Are Caused by Living Microscopic Cells (Fungi) That Are Not Spontaneously Generated”.

Transitions are, uniformly, nonexistent. Sections, chapters, and ultimately even the book itself simply stops, rather than concludes. The very last sentence wraps up a 300-page narrative, covering 2,500 years of Western science, this way: “The proof of this principle is demonstrated by the fact that one can obtain a pure preparation of viral particles that are specific for a particular host, infect that host, and recover from that host the identical viral particles that were used initially to infect the host.”

This roughness could have been reduced, without disturbing the underlying ideas, by judicious copyediting. The thin film of typographical errors and awkward phrasing that overlays it certainly should have been. Badly phrased sentences cause the 7th century to be the end (not the beginning) of Muslim expansion in Europe and The Black Death to spread west from Britain (not north and east from Italy) into Germany and Russia.

On pp. 64-65, a particularly unfortunate error in phrasing suggests that Santer agrees with a medieval commentator who advocated the burning of Jews at the stake. The date range of the Hippocratic Corpus changes by 100 years between pp. 31 and 33, and the name of the scientist discussed on pp.100-101 flips, seemingly at random, from “Thomas Hariot” to “Thomas Heriot”. The 12-page list of “Selected Readings” that concludes the book is a morass of inconsistent formatting, missing and misplaced italics, and duplicate dates that has to be deciphered rather than read.

This kind of inattention to detail—along with the lack of specific references for anything but block quotations—is unwelcome in any book. In one produced by a publisher known for exacting standards and high-quality products, one is left feeling perplexed.