Standing at the age of 30 from the Analects of Confucius, "I have five out of ten, but I am determined to learn." Stand at thirty. Forty without confusion. You knew your destiny at the age of fifty. Sixty sounds good. Seventy, and do what you want, don't go too far. "
"Standing at 30" means that people can stand on their own feet and achieve something in society at the age of 30.