Etymology of 三寸不烂之舌

Question

三寸不烂之舌 is used to describe great eloquence, similar to the English phrase "silver tongue". How exactly did this phrase come about? What does "三寸" mean? What's the meaning of "烂" in this phrase?

Some examples of its historical use include:

• 《水浒全传》第十五回：“小生必须自去那里，凭三寸不烂之舌，说他们入伙。”
• 《三国演义》第三回：“愿凭三寸不烂之舌，往江东说此人来降。”

Edit

I'm sorry if this question seems very basic, as I'm getting a few very basic responses. This is what should be obvious (and I'm not asking):

• 三寸 is a length, alluding to the tongue
• 烂 also has the meaning of "worn out"
• The literal meaning of "三寸不烂之舌" would be "a tongue that does not wear out", meaning someone who can speak at length with ease, hence eloquence.

What I'm not clear on, and I'm hoping there are some explanations, are:

• Why use 三寸, a length, to describe the tongue? Why not use something else, like weight or colour? Why use 三寸 to describe the tongue, as opposed to other body parts? What's the significance?
• 烂 has many meanings, so why pick the "worn out" one? Was the meaning of "worn out" more idiomatic during the origin of this phrase, as opposed to what it's usually used for now - tender or rotten? Why not use other characters to mean the same thing, is there a significance to using 烂?

I appreciate that in etymology, sometimes there are no good answers, or there were but are lost to time.

Answer 1

This is one of those phrases that have no 'official' etymology, but there exists multiple folk etymologies based on cultural allusions.

One of these allusions traces back to the Period of Warring States (战国时代). The state of Zhao (赵国) was being invaded by Qin (秦国). Out of desperation, the king of Zhao asked one of his officials to act as an ambassador to the state of Chu (楚国) to request for reinforcements. The official (平原君) selected 19 out of his thousands of followers to go with him, but had trouble selecting the last one to complete his entourage. One of the followers stepped forward and volunteered himself. His name was Mao (毛遂; this is also where the phrase 毛遂自荐 came from). Due to Mao's extraordinary talent of persuasion and speech, Chu agreed to send reinforcements. Here is a (rather abridged) section from the story:

平原君签定纵约返回赵国后曰：「我不敢再鉴识人才了。我鉴识人才多至上千人，少则数百人，自认为不会漏失天下贤能之士，现在竟遗漏毛先生了。毛先生一到楚国，就使赵国的地位比九鼎大吕的传国之宝还有���量。毛先生的三寸舌头，比百万大军还要强大。」

In this case, the official likened Mao's tongue to an army one million strong. Essentially, a human tongue is approximately 三寸 (or 10 centimetres), with 寸 being a Chinese traditional unit of measurement which is approximately 33.33 millimetres or 3.33 centimetres; 烂 means 'tattered' or 'worn' as in 破烂; 舌 or 舌头 means 'tongue'. A 三寸不烂之舌, or 10 centimetres of tongue that never wears out, therefore, refers to a person's ability to engage in often long discussions and persuade the other party to pursue your cause in the end.

There are other cultural allusions. All of the ones I have seen seem to originate from the Period of Warring States.

Answer 2

The original allusion was back in the Period od Warring States as deutschZuid has said. "三寸之舌，强于百万之师".

Now as to the question of why use 三寸. This is apparently the usage of parallelism which is one of the most common rhetoric in ancient China: [三(number)寸(unit)之舌(noun)]，强于[百(number)万(unit)之师(noun)]. Although 百万 is actually a number, it can be interpreted as "one hundred of 万", hence using 万 as an unit.

Then the last question left is why use 不烂 to describe the tongue. Notice that the oldest allusions were without these two characters. 不烂 was added to this phrase later on. Considering the etmology, the most sounding source should be the legend of Kumārajīva(鸠摩罗什), who was a famous 4th century Buddist and translator. Before his death he took an oath: "若所传无谬者，当使焚身之��，舌不焦烂"(roughly means, "if my translation works are without errors, my tongue shall not be burnt during the cremation of my body"), and it turned out, according to legend, his tongue did preserved after the cremation. Therefore 不烂 had since then merged in to the phrase 三寸之舌, somehow, to describe the great eloquent.

Answer 3

I don't remember what the story was, but this phrase is about 张仪。You should probably read 史记 or 战国策。张仪 is the student of 鬼谷子。And the story has something to do with a failed 游说。I am sorry I can't provide more details. But even if I do, I am not sure I can tell the story in English, I am not good at it.