The Master said,

‘At fifteen I set my heart upon learning

At thirty, I had planted my feet upon firm 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 a docile ear.

At seventy, I could follow the dictates of my own heart;

for what  I desired no longer overstepped the boundaries of right.

-Confucius, ANALECTS

For more about Confucius, see the Stanford Encyclopedia of

Philosophy at:

http://plato.stanford.edu/entries/confucius/