Editors Pick

Few biological encounters have shaped human history more subtly than surviving disease. Long before immunity became measurable in laboratories, societies had already observed its effects in uneven patterns of survival. Thucydides, writing about the plague of Athens, noticed that those who recovered could tend to the sick without falling ill again. Centuries later, Ottoman inoculation practices would travel through diplomatic correspondence into England, while exposure itself increasingly came to be understood not simply as danger, but as a form of biological instruction. Vaccination emerged from this slowly accumulating recognition, that is, the body can be altered by encounter long before it understands what it has encountered.