high horse (n.)youdaoicibaDictYouDict[high horse 词源字典]
originally (late 14c.) "fine, tall horse; war horse, charger" (high steed is from c. 1300), also, like high hall, "status symbol;" figurative sense of "airs, easily wounded dignity" in mount (one's) high horse "affect airs of superiority" is from 1782 (Addison has to ride the great horse in the same sense, 1716). Compare French monter sur ses grands chevaux; "The simile is common to most languages" [Farmer].[high horse etymology, high horse origin, 英语词源]