子曰：三十而立 Confucius said: At thirty, I could stand.

在中学读到孔子这句话时，自然而然的就把它解释为：人到了三十岁，就应该成家立业了。‘立’就是‘立业’的意思。这种说法对吗？
“三十而立。”三十岁孔丘就可以“立”了。
孔丘说：“不学礼，无以立。”《论语·季氏》。又说：“立于礼，成于乐。”《论语·泰伯》
冯友兰认为‘立’就是懂得了行事为人的准则。所谓“非礼勿视，非礼勿听，非礼勿言，非礼勿动”《论语·颜渊》，立就是学礼已经达到一定的程度，那么视、听、言、动，都可以循规蹈矩，不至于违反周礼，可以站得住。
李泽厚《论语今读》说：“‘三十而立’，有人强调与‘立于礼’有关，是指人从六岁‘习礼’到三十岁才算完全掌握熟练，但后世注疏多不拘泥于学礼，而泛指人格的成熟，更佳。”
南怀瑾《论语中的名句》说：“立就是不动，做人做事处世的道理不变了，确定了，这个人生非走这个路子不可。”
杨伯峻《〈论语〉译注》的译文：三十岁，懂礼仪，说话做事都有把握。
蔡尚思《孔子思想体系》也说：“‘三十而立’，也就是学有所成。”这个学有所成，不单纯指知识和学问，还包括一个人的人生观、世界观、价值观，包括一个人的人格。
举了这么多学者的注解，大家明白了吗？
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Confucius said: "三十而立 San Shi Er Li" .

How to translate this into English? Here are some translations that I found on the Internet:
"Be successful by thirty"
"At thirty, I could stand."
"At thirty, I stood firm."
"At 30 I firmly took my stand."
"At thirty I had a place to stand."
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Let's talk about 立 first. Here li (立) means to establish, that is to say, our knowledge and learning, including our life philosophy, world view, sense of worth and personality have become mature and established when we are 30.

It also means to stand, to make a stand.

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Now the question is: What actually do you want to establish? What 'stand' do you want to take? There are many possible interpretations here. This is because Confucius did not elaborate on the What. Many scholars interpret What to mean li (礼) by quoting Confucius' own words: "Take your stand ie li(立) in the li (礼)." (立于礼 li yu li). Confused?

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Now, let's talk about 礼. According to Confucius, li (礼) is defined as proprietary rites or good manners. The concept of li determines how you act in a given relationship. In other words, li can be viewed as a person's morality. A person's morality is responsible for how they act or react to certain situations as well as how they view the world. Confucius advocates the necessity of li as a stepping stone to social harmony. li is interpreted quite differently throughout Confucian philosophy.
Fung Yu-Lan: "Confucius also said: 'Take your stand in the li (rituals, ceremonies, proper conduct).' (Analetcs VIII, 8) Again he said: 'Not to know li is to have no means of standing.' (XX, 3) Thus when he said at thirty he could 'stand', he means that he then understood the li and so could practice proper conduct.