(lit.) the person from Zheng 鄭|郑[Zheng4] who wanted to buy shoes (an allusion to an ancient story about somebody who, when buying a pair of shoes, preferred to rely on their foot measurements rather than just trying them on) (idiom); (fig.) disregarding the sensible approach in favor of adherence to a fixed idea
trad. 鄭人買履
Also written 鄭人買履【zhèng rén mǎi lǚ】