“A good thing to think about is what kind of face to make when you say please,” Ruth Krauss wrote in her magnificent final collaboration with Maurice Sendak. “That coat will be the last gift [your mother] gave you. You will regret the small thing you didn’t say for the rest of your life. Say thank you,” Cheryl Strayed counseled in her endlessly soul-stirring Tiny Beautiful Things: Advice on Love and Life from Dear Sugar. But how did these commonest of courtesies, “please” and “thank you,” actually originate? That’s precisely what anthropologist and activist David Graeber explores in one of the most absorbing semi-asides in his altogether illuminating Debt: The First 5,000 Years (public library):

Debt … is just an exchange that has not been brought to completion. It follows that debt is strictly a creature of reciprocity and has little to do with other sorts of morality. . . . But isn”t that just the same old story, starting with the assumption that all human interactions must be, by definitions, forms of exchange, and then performing whatever mental somersaults are required to prove it? No. All human interactions are not forms of exchange. Only some are. Exchange encourages a particular way of conceiving human relations. This is because exchange implies equality, but it also implies separation.

Graeber goes on to offer a counterexample via the history of two of our most common cultural habits of civility:

Consider the custom, in American society, of constantly saying “please” and “thank you.” To do so is often treated as basic morality: we are constantly chiding children for forgetting to do it, just as the moral guardians of our society — teachers and ministers, for instance — do to everybody else. We often assume that the habit is universal, but … it is not. Like so many of our everyday courtesies, it is a kind of democratization of what was once a habit of feudal deference: the insistence on treating absolutely everyone the way that one used only to have to treat a lord or similar hierarchical superior.

But not all such courtesies are meaningless echoes of bygone hierarchical structures:

Imagine we are on a crowded bus, looking for a seat. A fellow passenger moves her bag aside to clear one; we smile, or nod, or make some other little gesture of acknowledgment. Or perhaps we actually say “Thank you.” Such a gesture is simply a recognition of common humanity, we are acknowledging that the woman who had been blocking the seat is not a mere physical obstacle but a human being, and that we feel genuine gratitude toward someone we will likely never see again.

Most fascinating of all, however, is the actual etymology of the two expressions:

The English “please” is short for “if you please,” “if it pleases you to do this” — it is the same in most European languages (French si il vous plait, Spanish por favor). Its literal meaning is “you are under no obligation to do this.” “Hand me the salt. Not that I am saying that you have to!” This is not true; there is a social obligation, and it would be almost impossible not to comply. But etiquette largely consists of the exchange of polite fictions (to use less polite language, lies). When you ask someone to pass the salt, you are also giving them an order; by attaching the word “please,” you are saying that it is not an order. But, in fact, it is. In English, “thank you” derives from “think,” it originally meant, “I will remember what you did for me” — which is usually not true either — but in other languages (the Portuguese obrigado is a good example) the standard term follows the form of the English “much obliged” — it actually does means “I am in your debt.” The French merci is even more graphic: it derives from “mercy,” as in begging for mercy; by saying it you are symbolically placing yourself in your benefactor”s power — since a debtor is, after all, a criminal. Saying “you’re welcome,” or “it’s nothing” (French de rien, Spanish de nada) — the latter has at least the advantage of often being literally true — is a way of reassuring the one to whom one has passed the salt that you are not actually inscribing a debit in your imaginary moral account book. So is saying “my pleasure” — you are saying, “No, actually, it’s a credit, not a debit — you did me a favor because in asking me to pass the salt, you gave me the opportunity to do something I found rewarding in itself!” …

Noting that “tacit calculus of debt” is “not the quintessence of morality but the quintessence of middle-class morality,” Graeber points out that the history of these exchanges, whether meaningless or meaningful, is actually a surprisingly recent development:

The habit of always saying “please” and “thank you” first began to take hold during the commercial revolution of the sixteenth and seventeenth centuries — among those very middle classes who were largely responsible for it. It is the language of bureaus, shops, and offices, and over the course of the last five hundred years it has spread across the world along with them. It is also merely one token of a much larger philosophy, a set of assumptions of what humans are and what they owe one another, that have by now become so deeply ingrained that we cannot see them.

Complement with Lord Chesterfield on the art of pleasing and the art of finding happiness in everyday gratitude.