Perhaps the greatest rudenesses of our time come not from the callousness of strangers, but from the solicitousness of intimates who believe that their frank criticisms are always welcome, and who feel free to “be themselves” with those they love, which turns out to mean being their worst selves, while saving their best behavior for strangers.

Judith Martin (b. 1938) American author, journalist, etiquette expert [a.k.a. Miss Manners]

Common Courtesy, “Those Who Would Change the Country’s Manners Encounter Citizen Resistance” (1985)
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