Dirt is matter out of place. A farmer does not call the fertile soil that nurtures her soybean crop “dirt.” But that same soil tracked by kids across the kitchen linoleum is definitely dirt, decidedly matter out of place. That simple fact reminds us that human preoccupation with purity and cleanliness is not so much about hygiene as it is about creating a sense of order.

And that helps us understand the interest of the Pharisees in purity, in keeping clear the borders between clean and unclean in the management of space, things, and human behavior. One of the glories of the Torah, celebrated in today's reading from Deuteronomy, is that the Mosaic laws covered all of life and integrated the ordinary business of civic life and household management with the worship of God. Thus all the details of one's life, properly ordered, were part of living out the covenant of one’s relationship with God. It was inevitable that the human passion for order, so often expressed in the separation of the clean from the unclean, should become an important part of this living of the divine Law.

And therein lay a danger in the Law: the focus on external purity of surfaces and behavior could itself become disordered and threaten the whole point of the Law—right relationships among people and between them and their God. It was an ancient problem, addressed often by the prophets; and now in this Sunday’s Gospel we hear Jesus join those prophetic voices, indeed quoting one of them (Isaiah), in calling people back to the basics. What Jesus says about a pure heart being more important than clean hands parallels exactly what he says in the Sermon on the Mount about attending to one’s lust and anger.

To drive his point home with his disciples, Jesus dares to draw an earthy analogy from their experience of digestion and defecation (missing from the Lectionary reading):

Do you not realize that everything that goes into a person from outside cannot defile, since it enters not the heart but the stomach and passes out into the latrine? … But what comes out of a person, that is what defiles. From within people, from their hearts, come evil thoughts, unchastity, theft, murder, adultery, greed, malice, deceit, licentiousness, envy [ophtholmos poneros, literally “evil eye”], blasphemy, arrogance, folly. All these evils come from within and they defile (Mark 7:18-23).