Meaning of 人不知而不愠，不亦君子乎？

We have prepared well for understanding the meaning of the third sentence of the most important classic of Confucianism： 《论语》: 人不知而不愠，不亦君子乎？ To start, we will review the meaning of each Chinese character of it.

人: https://xiongzou.blogspot.com/2011/12/learn-one-chinese-character-day.html
It is drawing of a person.

不: https://xiongzou.blogspot.com/2019/09/blog-post_22.html
It means not.

知: https://xiongzou.blogspot.com/2021/09/blog-post.html 
It is composed of 矢 and 口, which represents the meaning of some expert teaching / sharing knowledge of archery and warring weapon. And here it is used to mean knowing / understanding. 

而: https://xiongzou.blogspot.com/2019/08/blog-post.html
It is a drawing of a lot of long beard, which represents the relationship of equality or similarity of things it connects.

不: https://xiongzou.blogspot.com/2019/09/blog-post_22.html
It means not.

愠 | 慍: https://xiongzou.blogspot.com/2021/11/blog-post.html

It represents warming / heating up the heart, and is used to mean being angry or indignant.

不: https://xiongzou.blogspot.com/2019/09/blog-post_22.html

It means not.

亦: https://xiongzou.blogspot.com/2019/10/blog-post_28.html
It means same, as well or too.

君: https://xiongzou.blogspot.com/2019/02/learn-one-chinese-character-day_11.html

It is originally represent the person who holding the power and giving orders, which is eventually used to mean people with great heart or noble person.

子: https://xiongzou.blogspot.com/2011/12/learn-one-chinese-character-day_26.html

It is used to mean baby mostly, and it is used to mean Love and Respect especially as it is after 君 here.

乎: https://xiongzou.blogspot.com/2020/07/blog-post.html

It means shout loudly, or it can be understood as modal particle.

Before you check out our answer below, please take the last chance to try to reason the meaning of the sentence "人不知而不愠，不亦君子乎？" yourself.

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And here we go the answer:

Modern Chinese first: "不被人了解而不生气，这不就是君子吗？"

English next: "If a person can keep calm and patient while he is being misunderstood, is not he a noble gentleman?"

If you have a different mother tongue, you are welcome to provide translation for your own mother tongue. And of course if you have different translation for modern Chinese or English, you are welcome to provide your version as well.

That is all for today, let us enjoy again another Chinese calligraphy of "不知而不愠，不亦君子乎"

学而时习之，不亦说乎？有朋自远方来，不亦乐乎？人不知而不愠，不亦君子乎?

愠 | 慍

 After learning 温 | 溫, we now should be able to guess the meaning of our character today: 愠 | 慍, which is composed of 忄and 昷. 

We have known that忄means heart (心), whose details can be found at https://xiongzou.blogspot.com/2015/11/learn-one-chinese-character-day_20.html. And 昷 has the meaning of warming / heating up. 

Thus忄and 昷 together have the aggregated meaning of warming / heating up the heart, which logically represents "burning angry within the heart".

Let us examine the evolution history of 温 | 溫 to understand it better:

evolution history of 愠

From its Bronze script, we can tell that 愠 used to be same character as 昷, eventually Chinese ancestors added heart to 昷 to emphasize that 愠 is related to feelings.

愠 | 慍 means angry or indignant as adj, and resent or become angry as verb.

That is all for 愠 | 慍, time to enjoy a Chinese calligraphy with 愠 | 慍 inside:

参谋蜀耆英，棠阴满三郡。开怀接儿辈，色不见喜愠。
清朝贵老成，故家多黄训。佳气引春帆，长安天日近。