The word "zhi" here refers to the aforementioned "Tian Xingjian", which is often omitted in classical Chinese grammar. The direct translation of this sentence is that the operation of heaven is the most vigorous, and a gentleman makes himself strong and endless by conforming to this law (following heaven). Living between heaven and earth, of course, let nature take its course, and don't let a gentleman work hard and strive for self-improvement.
Extended data
Tsinghua's school motto, two sentences mean: heaven (that is, nature) is strong, accordingly, a gentleman should do things like heaven, strive for self-improvement, be resolute and vigorous, and not be lazy.
The earth absorbs sunlight and nourishes everything. A gentleman should increase his morality and set an example. A gentleman should run like a celestial body; If you are a gentleman, measurement should be like the earth, and nothing can't be loaded.
Baidu Encyclopedia-Tian Xingjian, a gentleman strives for self-improvement.