There are two ways of spreading light: to be the candle or the mirror that reflects it.

Knowledge is only one-half. Faith is the other.

Even the knowledge of my own fallibility cannot keep me from making mistakes. Only when I fall do I get up again.

There are three principal means of acquiring knowledge... observation of nature, reflection, and experimentation. Observation collects facts; reflection combines them; experimentation verifies the result of that combination.

I don't pretend we have all the answers. But the questions are certainly worth thinking about.

A man of knowledge lives by acting, not by thinking about acting.

Formula for success: rise early, work hard, strike oil.

I have never in my life learned anything from any man who agreed with me.

Cherish that which is within you, and shut off that which is without; for much knowledge is a curse.

It is one of my sources of happiness never to desire a knowledge of other people's business.