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.

But inner experience is only one source of human knowledge.

Every addition to true knowledge is an addition to human power.

There are no shortcuts in evolution.

Knowledge is like money: to be of value it must circulate, and in circulating it can increase in quantity and, hopefully, in value.

Opinion is the medium between knowledge and ignorance.

The greater our knowledge increases the more our ignorance unfolds.

Where there is no vision, there is no hope.

Be not simply good - be good for something.