Mi private opinyun iz, that politeness haz won more sudden viktorys than logick haz.

[My private opinion is, that politeness has won more sudden victories than logic has.]

Josh Billings (1818–1885) American humorist, aphorist [pseud. of Henry Wheeler Shaw]

Everybody’s Friend, Or; Josh Billing’s Encyclopedia and Proverbial Philosophy of Wit and Humor, ch. 243 “Missellaneous: Private Opinyuns” (1874)
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I have also seen second-hand reference (e.g.) to a variant of this -- "Politeness haz won more viktorys than logick ever haz" -- but have been unable to find it in Billings' works.