Getting Down and Dirty with Impurity

DAN PORGES / ALAMY STOCK PHOTO

Among the Hebrew Bible’s most obscure, perhaps even alien concepts is the notion of impurity. Modern readers may wonder what is to be gained from the detailed instructions pertaining to the pollution (ṭum’ah) caused by genital emissions, disease, corpses, and creepy-crawly creatures (Leviticus 11–15; Numbers 19). Why are we so reluctant to think about—let alone discuss—these aspects of our embodied experience? And why does the Bible cast a spotlight on these topics that are so often conveniently hidden from public view?

The British anthropologist Mary Douglas took an important step in confronting biblical purity laws in her classic treatise Purity and Danger (Routledge, 1966). In this work, Douglas famously equated pollution with “dirt,” which she then defined abstractly as “matter out of place.” From this premise, she sought to decode the symbolic systems manifested in purity laws. Although this approach has been remarkably influential on biblical studies, scholars in recent years have begun to question its tendency to recast the gory details of purity laws as representing abstract social or intellectual categories rather than addressing actual pollution.

An important step forward in understanding pollution came with the upsurge of interest in evolutionary psychological approaches to disgust over the past 30 years. These studies argued that the items that arouse our disgust (which are often the same ones associated with impurity) often pose dangers when ingested or touched. Along similar lines, recent psychological studies have focused on the perception that certain items cause “contagion,” the transfer of an unwanted invisible influence. This contagion can take multiple forms. Just as study respondents were reluctant to wear a sweater previously worn by a hepatitis patient, so too they were less than enthusiastic if the previous owner was a serial killer. These psychological studies can go a long way toward illuminating why the same sources arouse a fear of dangerous contagion (impurity) in cultures around the world. Moreover, they suggest that this seemingly “religious” concept may actually be rooted in our biological nature.

The ancient Near Eastern evidence fills a crucial gap in our understanding of the historical process by which our ideas about purity developed. As it turns out, for human societies that had yet to discover microscopic germs, notions of pollution played a vital function in pathogen avoidance. Letters from the Syrian city of Mari in the early 18th century BCE provide us with the earliest unambiguous evidence of how they understood and responded to infectious disease. For example, one letter that I have translated reads:

The god is striking in the upper district, so I without delay took a bypass. Furthermore, my lord should give orders that the residents of the cities that have been touched [laptūtu] not enter cities that are not touched, lest they touch [ulappatū] the whole land. And if there will be a campaign of my lord to the upper district, my lord must stop in Terqa. He must not move on to Saggaratum. The land is “touched” (i.e., infected).¹

Even as the people of Mari interpreted the epidemics that devastated the region as expressions of divine anger, their public policy was much more down to earth, focusing on the quarantining of infected people and cities. These measures may seem all too familiar to us in the wake of the recent COVID-19 pandemic. Even the peculiar idiom “touched” (Akkadian lapātu) used in regard to the infected cities is in fact an exact semantic parallel of the word “contagion,” from Latin com-tangere (“touched with”). Semantic parallels can also be found in biblical Hebrew ng‘ and ancient Greek epaphe, both with the concrete meaning “touch” used to describe the spread of disease. These parallels reveal the commonality in the way pre-modern cultures understood the experience of infectious disease.

Additional letters from Mari show how an awareness of contagion influenced domestic life. One letter from Queen Shibtum to King Zimri-Lim relates that her infected servant was placed in an isolated dwelling where she would eat her meals separately from the rest of the palace servants: “No one will approach her bed or chair.” In a letter from Zimri-Lim to Shibtum, the king expresses concern regarding another infected servant who had been freely interacting with the personnel: “Now command that no one will drink from a cup that she drinks from, nor sit in a chair in which she sits, nor sleep on a bed in which she sleeps!” This awareness also finds expression in rituals from the early first millennium BCE. For example, the Mesopotamian Shurpu (“burning”) incantation refers to contracting a “curse” by means of touching furniture or consuming food or drink touched by a “cursed” (tamû) person.

These sources provide crucial background for understanding the biblical laws of impurity. Two of the most severe sources of ṭum’ah, requiring banishment and elaborate sacrificial rituals, pertain to skin disease (Leviticus 13) and uncontrollable genital flows (Leviticus 15). Each type of pollution bears unique characteristics that determine how it is transmitted and how it is to be purified. For example, the impurity of genital flows is spread by means of furniture upon which the infected person has sat or lain, creating an invisible stain on these objects. On the other hand, corpse impurity spreads like a gas within a closed space (literally a “tent”), an understanding modeled after the spread of a decomposing corpse’s odor, which was associated with the release of the dead person’s soul (nefesh) from the corpse.

Yet, alongside these physiological sources, the Hebrew Bible also refers to pollution caused by certain types of transgression. Scholars have labeled these instances “moral impurity,” though it is important to recognize that nearly all of the relevant examples pertain to the domain of illicit sexual relations. Although it seems reasonable to view these examples, which appear primarily in the Holiness Code (Leviticus 17–26), as metaphorical, one should recognize that the association of impurity with sexuality is not arbitrary. As with genital emissions more generally, sexual violations are depicted as leaving a metaphysical stain that threatens the perpetrator—and even the community at large—with divine retribution. This metaphorical extension of purity language also finds analogies cross-culturally, not only among traditional cultures but even in modern Western society, where the topic of “moral disgust” has garnered considerable attention in recent years.

Taken together, these examples demonstrate how a supposedly religious idea such as impurity is deeply rooted in embodied experience. This recognition allows us to appreciate that the notion of pollution is based on psychological intuitions that have facilitated human survival from prehistoric times until the present day. Moreover, this embodied discourse provided a repertoire of images that could be used to express attitudes toward certain types of moral violations. In these ways, the repertoire of bodily experience provides the imagery for discussing the hidden causal forces that shape our physical and social realities.

Among the Hebrew Bible’s most obscure, perhaps even alien concepts is the notion of impurity. Modern readers may wonder what is to be gained from the detailed instructions pertaining to the pollution (ṭum’ah) caused by genital emissions, disease, corpses, and creepy-crawly creatures (Leviticus 11–15; Numbers 19). Why are we so reluctant to think about—let alone discuss—these aspects of our embodied experience? And why does the Bible cast a spotlight on these topics that are so often conveniently hidden from public view? The British anthropologist Mary Douglas took an important step in confronting biblical purity laws in her classic treatise Purity […]