This sentence introduces a deeper meaning: the universe keeps running, and people should follow the example of heaven and earth and keep moving forward forever.
The complete sentence of this sentence is: Tian Xingjian, the gentleman is constantly striving for self-improvement; The capacity of the earth is limited, so a gentleman must constantly cultivate his own virtue to undertake the world. This sentence is now the school motto of Tsinghua University
Extended data:
The sentence "Heaven is strong, and gentlemen are constantly striving for self-improvement" comes from Zhouyi. The Book of Changes, one of the Three Changes of the Book of Changes (another view: the Book of Changes is three changes, not the Book of Changes), is one of the traditional classics. It is said that it was written by Zhou Wenwang Jichang, and its contents include the Book of Changes and the Book of Changes. Classics are mainly composed of 64 hexagrams and 384 hexagrams, each of which has its own interpretation (hexagrams) for divination. The Book of Changes did not put forward the concepts of Yin-Yang and Taiji, but was influenced by Taoism and Yin-Yang theory. Biography contains seven kinds of words to explain hexagrams, a total of ten articles, collectively known as "Ten Wings", which is said to be written by Confucius.
During the Spring and Autumn Period, official schools began to evolve into private schools. There is a gradual development before and after the Yi-ology, and a hundred schools of thought contend, so it is easy to divide. Since Confucius praised the Book of Changes, the Book of Changes has been regarded as a Confucian classic and the first of the Six Classics by Confucianism. In addition to Confucianism, there are two schools of Yi-ology and Confucianism-Yi-Yi, which develop in parallel: one is Yi-ology, which still exists in the old forces; The other is Laozi's Taoist Yi, which began to be divided into three branches.
References:
Baidu encyclopedia-Zhouyi