The only source of knowledge is experience.

The desire of power in excess caused the angels to fall; the desire of knowledge in excess caused man to fall.

I keep six honest serving men (they taught me all I knew); Their names are What and Why and When And How and Where and Who.

Knowing your own darkness is the best method for dealing with the darknesses of other people.

No man can reveal to you aught but that which already lies half asleep in the dawning of your knowledge.

To furnish the means of acquiring knowledge is the greatest benefit that can be conferred upon mankind. It prolongs life itself and enlarges the sphere of human existence.

There is much pleasure to be gained from useless knowledge.

When you know a thing, to hold that you know it; and when you do not know a thing. To allow that you do not know it—this is knowledge.

It is always advisable to perceive clearly our ignorance.