At fifteen I set my heart upon learning.
At thirty, I had planted my feet firm upon the ground.
At forty, I no longer suffered from perplexities.
At fifty, I knew what were the biddings of Heaven.
At sixty, I heard them with docile ear.
At seventy, I could follow the dictates of my own heart; for what I desired no longer overstepped the boundaries of right.

Author: Confucius