固若金汤

Pronunciation: gù ruò jīn tāng Literal meaning: Metal walls, a moat of boiling water

Origin & Usage

In the Book of Han, Kuai Tong warns what will follow if the magistrate who surrendered first is put to death: the other border towns will hear of it, wall themselves up, and 皆为金城汤池，不可攻也 — all become walls of metal and moats of scalding water, and cannot be attacked. The warning is conditional and about what has not happened yet, not a report of cities already impregnable. 汤 is the trap for learners: here it is boiling liquid, not soup, and the moat is heated rather than merely wet. The four characters compress it — solid (固) as (若) metal (金) and scalding water (汤) — one defence passive and one active. Chinese uses the phrase for fortifications, for alibis with no hole in them, and for systems built with several independent layers.

Examples

English: "The company's cybersecurity defenses were impenetrable to attackers"

Chinese: 公司的网络安全防御对攻击者来说固若金汤