Confucius, who came from the Analects of Confucius at the age of thirty, said, "I am determined to learn five out of ten, stand at the age of thirty, be not confused at forty, know my destiny at fifty, listen to my ears at sixty, and do what I want at seventy, without exceeding the moment." Confucius said "standing at the age of 30", which means that at this time, he acted according to the ceremony and behaved appropriately. Now it is often used to indicate that people (thirty years old) have begun to achieve something.
Forty-year-old people are not confused from The Analects, which shows that they have experienced a lot and have their own judgments (mainly value judgments, that is, judging right and wrong, good and evil, beauty and ugliness ...), and life is no longer confused and confused.