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Book Summary: Purity and Danger – Investigations on the Human Obsession With Dirt and Cleanliness

Purity and Danger (1966) presents a framework for understanding different societies and religions according to what they find pure and sacred and what they consider unclean and out of place. Cultures organize their experiences, values, and worldview into binary categories: either something is “dirty” and does not belong, or it is pure or holy. Sometimes, something – or someone – is both or neither. By looking at how other cultures make these distinctions, you can become more aware of how your own is organized.

Introduction: Learn how our perception of what is dirty and what is sacred shapes our worldview.

You sit down for dinner. Just as you start eating, a pair of boots, caked in mud after a long day of garden work, is slammed onto your kitchen table. Gross. But hang on a moment. Would you say that the boots themselves are dirty? Or are they just not where they belong? And while the soil on the shoes may be dirty in your kitchen, would you still consider it dirty if it were in the garden, keeping your precious rhododendrons alive?

Book Summary: Purity and Danger - Investigations on the Human Obsession With Dirt and Cleanliness

In her 1966 classic, Purity and Danger, author Mary Douglas questions the idea that objects or actions are unclean regardless of context. She proposes the opposite. By putting experiences into categories, such as dirty and pure, cultures can create order from an otherwise chaotic experience. Dirt and taboos keep these categories separate, and enforcing these distinctions hold societies together. When something, or someone, threatens this order, it becomes dangerous.

In these summary, we’ll look at how Douglas extends this idea to describe – and criticize – how many earlier Western anthropologists had written about religions and cultures other than their own. These writers were often seeking to demonstrate that certain cultures were superior and “more evolved” than others. And, as you might expect, there was usually a one-way prejudice: those who subscribed to the larger religions more common in Western societies – often predominantly Judeo-Christian – were characterized as superior, and more deserving of fair academic study. Followers of smaller religions in non-Western and sometimes non-literate societies, on the other hand, were deemed inferior, and less deserving of attention.

These classifications are a problem for Douglas. But she provides an alternative way to interpret cultures and experiences: a system of comparing conceptions of dirt and purity across societies. Viewing one culture through the lens of another means that one is always going to seem out of place. By learning what one culture considers dirt or taboo in its own context, you can gain deeper insight into how people in that culture experience life.

As you’ll see, these ideas are closely linked to how societies decide what or who is holy or sacred, in addition to how different cultures deal with ambiguity – that is, people or rituals that don’t fit into either category of unclean or sacred.

What’s so dirty about dirt?

Think back to your early childhood. Were you ever given any warnings of what to do to avoid something bad happening? Perhaps you were told such micro-taboos. For example, if you didn’t eat enough spinach or broccoli, you wouldn’t grow big and strong. Or maybe you were told that some catastrophe would happen, however fantastical and unlikely, if you didn’t go to bed on time.

Each of these warnings comes with a danger, a risk. This consequence for breaking the rules influences your behavior – and what you think is correct or inappropriate in your society. In other words, you learn from a young age what is unclean.

So what’s the reason for all this fuss? Well, the story goes that, if a community commits to recognizing certain ideas or objects as dirty or taboo, it is more likely to survive. By recognizing the same set of dangers, members stick together and have a unified experience.

Douglas defines dirt as matter that’s out of place. But how we make these decisions is far from universal. After all, dirt is relative, and only exists, as she writes, “in the eye of the beholder.” In other words, its uncleanness depends on its location, and whether we think it fits according to rules that we’ve learned – like those muddy boots on the kitchen table. If you thought that was gross, you probably learned at some point that dirt-encrusted footwear doesn’t belong on the table while you’re eating.

When we consider something dirty, it is a threat – a danger – to the rules and order you know and love. But each society is its own private universe, with its own set of customs, even if its conventions can still be influenced by outside factors. In one place, eating with your hands might be viewed as impolite or unhygienic by some: “Hands don’t belong in food,” they might say. In other places, it’s the norm, while eating with cutlery is considered unusual.

But much larger taboos than hygiene guidelines often play a more substantial role in ensuring that members of a community follow a pattern of conduct and maintain social order, especially when it comes to morality and spirituality. Now, these restrictions play out in different cultures in diverse ways, including dietary restrictions, warnings about sorcery and incest, and rituals for curing illnesses. In the following sections, you’ll get an idea of a few of these, as well as Douglas’s recommendations for how to interpret them.

Chewing the cud

At this point, we’re about to dive into an example that has perhaps received the most critical attention from this book. But please keep in mind that there’s a caveat, one that you’ll hear about at the end of this section.

Get ready! The example of the hour is… pigs. They live on farms, they make funny noises – you know all about them. But what’s a pig got to do with purity?

In the Old Testament, the Book of Leviticus XI outlines many dietary laws for followers of ancient Judaism to observe. Oxen, sheep, and goats are okay to eat, for example, but camels and rock badgers and hippopotamuses are considered unclean – and abominable. Douglas questions the explanations for these restrictions. Specifically, she singles out the command to avoid eating pork.

According to this book of the Bible, pigs are unclean because they have a “cloven hoof” but do not “chew the cud” – that’s just when animals partially digest food, and then move the food back into the mouth, chew it again, and then swallow. Appetizing, huh? Cows, sheep, and goats do this, but pigs do not.

The origins of this dietary guideline have been widely debated for centuries. Some have said it was originally a question of hygiene and health – pigs were sometimes a risk to both. You might’ve heard variations on this before: that pigs carried certain diseases, for example, or that refraining from eating pork in Judaism, Islam, and others was a matter of safety due to the hot climate of today’s Middle East. This school of thought aims to explain rituals through hygiene and physiology. It’s known as medical materialism, and Douglas firmly rejects it. She also dismisses another common interpretation, that such ritual beliefs are completely random and have no connection to a culture’s view of uncleanness.

Instead, she writes that the instruction not to eat pork is much more an external, physical expression of the ancient Jews’ goal to be spiritually pure and achieve holiness. Since each of the sections in the Book of Leviticus repeats the phrase “be holy, for I am holy,” by restricting these foods and behaviors, one can become holy – or at least closer to God.

And now for a fun fact interlude about the word “holy.” Sacred rules, such as these dietary laws, are also a way of separating – you could say, dirt from purity. The Latin word for holy, sacer, is related to a sense of restriction. Similarly, the Hebrew root for holy, k-d-sh, is also related to separation or setting something apart. In some translations of Leviticus, such as in the theologian Ronald Knox’s version, the phrase “be holy, for I am holy” is even translated as “I am set apart and you must be set apart like me.”

Finally, as promised at the beginning of this section, here’s the caveat to this whole section, which came nearly 40 years after Purity and Danger was first published: In the preface to the 2002 edition, Douglas confesses to some mistakes in her interpretation of why pigs were off limits but cows, sheep, and goats were not. Among her three main mistakes, she wrote, the most major one was to assume that a rational, compassionate God would even create so-called abominable creatures in the first place.

Rethinking what’s primitive and modern

Before we move on, a quick note on terminology: Douglas uses the words “modern” and “primitive.” These are the same words that earlier anthropologists and religious scholars, especially throughout the 19th and early 20th centuries, had used to describe what they called more and less “advanced” cultures and belief systems. These earlier voices tend to argue that such primitive societies lived according to fear, whereas modern societies were more based on science and rational thought.

Douglas, writing in the 1960s, criticizes this earlier usage and definitions, though she defends using the same terminology. She would later write that this was a way, based in racism, of discrediting or looking down on foreign cultures and religions.

She also suggests an alternative explanation. Primitive cultures center around the individual’s attempts to interpret one’s experiences. Each person has a close connection with the forces of the universe – such as the elements. When someone does or experiences an event, they directly interact with the universe.

Take, for example, the !Kung Bushmen in what is today called the Republic of Botswana. The !Kung people believe that they can influence the weather by releasing a force called N!ow. This happens when a hunter wears a kind of makeup resembling the animal he has just killed. The meteorology constantly changes depending on the complex combinations of hunters and successfully hunted.

Ambiguity: when something is both sacred and unclean

In some cultures, the lines between uncleanness and sacredness become obscured, or polluted. Take the dietary restrictions of the Lele people of the Kasaï-Occidental, a former province in the Democratic Republic of the Congo.

What the Lele should and shouldn’t eat is, for the most part, very clearly laid out. Only men can eat certain parts of animals, while other parts are just for women, and still others exist just for children, or pregnant women. Certain animals are entirely off limits for everyone. So far, so good. But when it comes to animals with an ambiguous status, things start getting more interesting.

Flying squirrels are neither birds nor completely earth-bound animals, so they’re to be avoided by adults, though apparently it’s sort of okay if children eat them. There’s no danger or punishment for doing so; they just advise against it.

Another animal with ambiguous status in the Lele community is the forest pangolin, also known as the scaly anteater. The pangolin transcends even more of the Lele culture’s typical categories. As its name suggests, the pangolin has scales, similar to those of a fish. But – and this is key – it can climb trees, unlike a fish. Unlike most other scaled creatures, too, the pangolin gives birth one at a time and nurses its young.

For the Lele people, the pangolin is unique. It’s the animal counterpart to humans who give birth to twins. Both pangolins and parents of twins are believed to be sources of fertility. You can see this in the Leles’ formal rituals. Unlike the flying squirrel, which is considered an anomaly and generally avoided, the pangolin has a special status. When members of the Lele community eat the pangolin’s meat as part of a ceremony, they are thought to receive its fertility.

Here, this in-between state isn’t a drawback; it symbolizes power. The pangolin is at once unclean, since it’s not for casual dining. But it’s also sacred, since it plays an important role for the community’s survival in creating future generations.

Witches and sorcerers: when someone doesn’t fit the mold

Now, not all cultures worship cases of ambiguity. Certain humans exist outside the typical patterns of society. They are in what Douglas calls a marginal state. Basically, the people of their community cannot explain whether these marginal-state people belong or not, whether they are unclean or pure. That makes them seem dangerous.

Depending on the culture and the reason for their anomalous status, these people are frequently viewed as witches or sorcerers. Unborn children also often count as being in a marginal state when cultures can’t explain their existence as living or not yet alive.

As with the flying squirrels and pangolins in the Lele people, this can take a turn in a few directions.

On the one hand, people in marginal states can be viewed as a threat, to be avoided. Perhaps they’re not dangerous themselves, but their community might think they attract fear or bad luck. Or they might be believed to release evil powers unto the world through their actions.

Take, for example, the fear of the evil eye, which is present in many cultures and religions and is thought to exert some kind of spiritual curse on the victim. Alternatively, if someone is suspected of having magical powers, they could also be feared for producing external symbols of evil, such as their ability to cast spells, curses, or other forces with harmful consequences.

Certain societies draw a distinction between witchcraft and sorcery. Those thought to practice sorcery could use their powers for good or evil. In Central Africa, for example, sorcery is sometimes used in medicine. Some cultures even recognize those with heightened spiritual power by giving them positions of authority in the community, as well as the power to bless or curse its members.

In European history, Joan of Arc might be considered to have existed in a marginal state for several reasons. She was a woman who wore armor and men’s clothing; she fought in battles; she was accused of witchcraft; and she was born a peasant but claimed to have divine inspiration.

For modern-day examples of people in marginal states, Douglas suggests formerly incarcerated individuals and former residents of psychiatric hospitals. In general, society views these people with an intolerant and suspicious attitude; they represent a danger because they seem out of place.


Dirt is matter out of place. By deciding what is unclean and what is pure or sacred, societies put the world into categories. It’s a way of understanding and interpreting experience according to these patterns, as well as establishing and maintaining order in a community. All cultures do this differently. Their rules and rituals help decide what belongs and what – or who – is dangerous. People in marginal states don’t fit into either category, and how cultures treat them varies.


Religion, Spirituality, Society, Culture, Anthropology, Philosophy, Sociology, Theory, Academic, Psychology, History, Social Science, Customs and Traditions Social Sciences, General Anthropology, Cultural Anthropology

About the author

Mary Douglas was one of the most distinguished anthropologists of modern times. Natural Symbols, another of her major works, is also available in Routledge Classics.

Table of Contents

Chapter 1 Ritual Uncleanness
Chapter 2 Secular Defilement
Chapter 3 The Abominations of Leviticus
Chapter 4 Magic and Miracle
Chapter 5 Primitive Worlds
Chapter 6 Powers and Dangers
Chapter 7 External Boundaries
Chapter 8 Internal Lines
Chapter 9 The System at War with Itself
Chapter 10 The System Shattered and Renewed


Is cleanliness next to godliness? What does such a concept really mean? Why does it recur as a universal theme across all societies? And what are the implications for the unclean?

In Purity and Danger Mary Douglas identifies the concern for purity as a key theme at the heart of every society. In lively and lucid prose she explains its relevance for every reader by revealing its wide-ranging impact on our attitudes to society, values, cosmology and knowledge. This book has been hugely influential in many areas of debate – from religion to social theory. With a specially commissioned preface by the author which assesses the continuing significance of the work, this Routledge Classics edition will ensure that Purity and Danger continues to challenge, question and inspire for many years to come.


“Professor Douglas writes gracefully, lucidly and polemically. She continually makes points which illuminate matters in the philosophy of religion and the philosophy of science and help to show the rest of us just why and how anthropology has become a fundamentally intellectual discipline.” – New Society

“Professor Douglas’ book sparkles with intellectual life and is characterised by a concern to understand. Right or wrong, sound or idiosyncratic, it presents a rare and exciting spectacle of a mind at work.” – Times Literary Supplement

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