Having referred a few times to the concepts of purity and purification, maybe we should circle back and talk about what those mean.

If your thoughts immediately went to the online meme of the “purity test,” you’re not entirely wrong. That checklist of sexual and sex-adjacent acts hints at the idea that you’re “stained” by such behavior — an attitude that shows up in full force when you start looking at, say, evangelical Christian attitudes toward sex before marriage. Those offer a constant drumbeat of imagery that associates the non-virgin bride with something irreparably soiled, like a chewed-up piece of gum. It’s about more than just her body; she herself is made worthless by the act.

But it isn’t all about sex. So let’s step back and look at the bigger picture.

Impurity, in a spiritual context, is a metaphysical contamination, and it’s distinct from sin; it’s not about doing something wrong. It may be associated with bodily matters — in fact, it often is — but the stain goes deeper than the flesh. Impurity can make someone unfit to engage in certain religious acts until they are cleansed. It can cause them to pollute those who come into contact with them. Sometimes it’s actively dangerous: a tainted individual has the power to blight and curse, causing misfortune, withering crops, even harming unborn babies.

(Because these essays are written with an eye toward the use of these concepts in stories, that power may sound cool. In societies where this kind of thing is seen as real, though, it is definitely not admired.)

What makes you impure? As I said above, it’s often linked to the body. Elimination of waste might be a minor defilement; washing your hands afterward is a good idea anyway, but it might be required before you’re allowed to touch sacred things or engage in certain rituals. In some cases sex is also considered polluting — not because it’s inherently bad, but because it involves the emission of bodily secretions from a region of the body that’s already pretty suspect.

The two big sources of impurity, however, are blood and death. There’s a reason why, if society has some kind of “untouchable” caste, they probably engage in occupations deeply concerned with such forces: butchers, executioners, gravediggers, and so on. Coming briefly into contact with blood and death is polluting, but when your life involves regular and sustained interaction with them . . . it’s not hard to see why the stain starts to look indelible.

What about warriors, though? Here, we see the double standard at work. After all, their occupation involves killing: maybe less often than a butcher cuts up a carcass or an executioner hangs a person (especially once you factor in how many deaths in war don’t happen right there on the battlefield), but they’re still murdering their fellow humans. But warriors also tend to be — not always, but often — among the elites of their societies. It isn’t that they aren’t defiled by combat; they very well may be! That contamination, however, is seen as removable, not inherent. Purifying men becomes a routine post-battle or post-war activity, part of how they shift gears back to domestic life.

Women, by contrast, very much get the short end of this stick. If blood is polluting, then being an adult woman generally involves a regular cycle of contamination. I’m not going to rehash Year Four’s coverage of practices around menstruation, but refer there for discussion of the ways in which the impurity of that gets handled. Childbirth likewise involves quite a lot of blood and, particularly in the historical past, a high risk of death for mother, child, or both: that fraught, liminal act may leave all parties in need of purification before they’re allowed to return to normal life. To us that sounds like a negative thing, and indeed it can be so; on the other hand, it can also mark out a stretch of time for recovery.

Even when there’s a positive angle, though, attaching the notion of impurity to menstruation and childbirth tends to have an underlying negative effect. Look a few paragraphs back to the discussion of untouchables and their indelible pollution; now look at the situation women are in. No few religions have denied women full participation in key ritual activities, positions of power, or even access to sacred spaces because they will never truly be pure. (Exceptions can be made for pre-pubescent girls or post-menstrual elders, but as far as I know, they usually aren’t.) This, in turn, loops us back around to that question of whether sex is a source of contamination: sometimes the answer is “yes” because it involves contact with women, and specifically with the most impure part of them.

Assuming that a person’s impurity can be removed, how does one go about doing that? Unsurprisingly, physical washing is the number one method, though sometimes the cleansing is more symbolic than anything else: witness the little dippers for water at many religious sites in Japan (they spread to Buddhist temples from Shintō shrines), or the Islamic practice of tayammum (a dry cleansing used in situations of water scarcity, or where full washing would cause problems). In some cases ordinary water suffices; in others, you need a properly sanctified ritual bath, or running water, or salt water.

Salt is a great symbolic source of purity overall, which is why it crops up so often as a way to repel demons and the like. In Shintō — that being a religion greatly concerned with purity — it’s used to cleanse people after funerals, and set in dishes to keep away evil spirits. Also, if you’ve ever seen a Shintō priest wielding a stick with one or more white paper streamers attached, that’s an ōnusa, which acts as a kind of magnet to draw impurity off of people or objects. Because people aren’t the only things that can be impure! Pollution can attach to places and items, too, especially if they’ve been connected with death or blasphemous acts. Just as with a person, physically cleaning the object or space may be part of how you purify it.

In worldbuilding, though, you don’t have stick purely to washing as the route to purity. The real world contains any number of other methods; they’re just individually less widespread. Roll an egg over someone’s body — especially a white egg? Fan them with a special fan? Prayers are pretty common, especially if they’re conducted by a duly authorized religious leader. The important thing, from a setting perspective, is whether the reader can see why that act is considered cleansing. They’ll have a hard time believing in a purification rite that involves dung.

And, as with all our ascetic topics this month, you have the question of what metaphysical effect, if any, this has in your world. Maybe your spiritually-based magic really doesn’t work if the character is polluted, because the divine powers won’t answer them in that state. Maybe someone can use their defiled state to blight those around them. It’s up to you . . . but if you go this route, remain aware of the political dimensions noted above, the ways in which these principles have been used to oppress entire groups of people. You don’t have to mimic those patterns, but you should know how they happened, and take that duly into account.