The Harvard Classics Volume 38 gathers fourteen scientific papers spanning two millennia, from Hippocrates' Oath to Louis Pasteur's germ theory. The excerpts show that these are not mere historical curiosities: each author builds a case from specific observations. William Harvey describes dissections and ligature experiments to argue that blood circulates; Edward Jenner presents detailed case histories of patients exposed to cowpox and smallpox; and Sir Charles Lyell challenges prevailing assumptions about geological change. The volume's structure—moving from ancient medicine through surgery, vaccination, and germ theory to geology—traces a shift from professional codes to experimental proof.

Hippocrates and the Origins of Medical Ethics

The volume opens with Hippocrates' Oath and Law, texts that establish medicine as a regulated craft. The Oath invokes Apollo, AEsculapius, and other deities, binding the physician to teach disciples without fee and to keep patients' confidences. The introductory note states that Hippocrates was a contemporary of Herodotus, born on Cos between 470 and 460 B.C., and that only five or six of the works attributed to him are considered genuine. The famous first Aphorism—"Life is short, and the Art long; the occasion fleeting; experience fallacious, and judgment difficult"—is quoted to show that this maxim originally referred to the physician's art. These documents reveal that professional standards for training and conduct were already codified in ancient Greece, a foundation that later papers in the volume build upon.

Jenner's Case-Based Argument for Vaccination

Edward Jenner's papers on vaccination rely on detailed case histories rather than theoretical claims. In one excerpt, he describes two sisters exposed to scarlatina: one showed a faint rash that disappeared as the cowpox pustule developed, then the scarlatina returned after the pustule dried. Jenner uses this sequence to argue that cowpox temporarily suppressed the other disease. He also addresses the concern that cowpox protection might be temporary, citing a person who resisted smallpox 53 years after cowpox. To refute the idea that cowpox spreads by effluvia, he reports experiments where uninfected children breathed over pustules without effect. These passages show Jenner's method: he presents specific cases, anticipates objections, and tests them with controlled observations.

Harvey and Lyell: Observation vs. Prejudice

William Harvey's On the Motion of the Heart and Blood and Charles Lyell's geological essays share a rhetorical strategy: they confront entrenched beliefs with direct evidence. Harvey's work, as excerpted, describes experiments with ligatures and dissections to demonstrate that blood circulates—a claim that contradicted Galenic medicine. Lyell's essay "Prejudices Which Have Retarded the Progress of Geology" argues that assumptions about the Earth's age and catastrophic change have hindered science. Both authors appeal to uniform principles: Harvey to the mechanical action of the heart, Lyell to uniformity in past changes. The excerpts do not include their full arguments, but the pattern is clear: each writer identifies a prevailing error and counters it with systematic observation.

Readers approaching this volume should note that the papers are arranged chronologically but not thematically; the connections between, say, Harvey's circulation and Pasteur's germ theory emerge only by reading across sections. The excerpts provide a sampler of each author's style—from Hippocrates' concise oaths to Jenner's clinical narratives—but the full texts contain more detailed evidence. Pay attention to how each writer handles uncertainty: some, like Jenner, hedge their claims with case counts; others, like Lyell, assert principles boldly. This collection rewards a comparative reading of methods as much as content.