Meaning: Confucius decided to study at the age of fifteen. The thirty-year-old learning foundation has been established, and personal values have been formed, which will not be shaken by external forces. By the time I was forty, I had mastered certain rights. At this time, I am relatively smart and can't do anything. Knowing the destiny at fifty, that is, the regular changes of everything in a cycle, nothing is incomprehensible. Hearing ears at the age of 60 means listening to hidden sounds with your ears. This is what the speaker really thinks. At the age of seventy, you can do whatever you want, but you don't overstep the bounds. Desire is spontaneously restricted to wander freely in the rules.
After the change: sixty flowers, seventy rare.
Meaning: Sixty is the year of sixty (China has used heavenly stems and earthly branches as the calendar year since ancient times, and sixty is sixty years, so sixty is also called sixty years).
Seventy-year-old is rare: from Du Fu's "Two Poems of Qujiang", "Wine debts are common, and life is seventy years old." That is, there are very few people who live to 70 years old (the average life expectancy in ancient times was low).