Without feelings of respect, what is there to distinguish men from beasts?

he who will not economize will have to agonize

It is when those who are not strong enough have made some moderate amount of progress that they fail and give up...

Wisdom, compassion, and courage are the three universally recognized moral qualities of man.

The wise never doubt. The Humane never worry. The brave never fear.

I am not one who was born with great wisdom. I love the ancients and diligently seek wisdom among them.

Am I a man of great wisdom? Hardly! Even when a simple person brings me a question, my mind goes utterly blank, I just thrash it out until I’ve exhausted every possibility.

Give me a few more years so that I am studying at fifty, and surely I may avoid major errors.

To know that you know, and to know that you don't know - that is the real wisdom.