The very essence of politeness seems to be to take care that by our words and actions we make other people pleased with us as well as with themselves.

[Il me semble que l’esprit de politesse est une certaine attention à faire que par nos paroles et par nos manières les autres soient contents de nous et d’eux-mêmes.]

Jean de La Bruyère (1645-1696) French essayist, moralist

The Characters [Les Caractères], ch. 5 “Of Society and Conversation [De la Société et de la Conversation],” § 32 (5.32) (1688) [tr. Van Laun (1885)]
    (Source)

(Source (French)). Alternate translations:

The Politeness of the Mind is a certain care to make us pleasing by our discourses and manners to our selves and others.
[Bullord ed. (1696)]

Politeness seems to be a certain Care, by the manner of our Words and Actions, to make others pleas'd with us and themselves.
[Curll ed. (1713)]

Politeness seems to be a Care to model our Discourses and Manners so as to please ourselves and others.
[Browne ed. (1752)]

It seems to me that the spirit of politeness lies in taking care to speak and act in such a way as to make others pleased with us and with themselves.
[tr. Stewart (1970)]