How We Got "Please" and "Thank You" →
Maria Popova, at brain pickings, has this fascinating look at the history of why we say "please" and "thank you".
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!” …