The is only one thing worse than knowing something; assuming it.

Only a blind man can easily define what light is. When you do not know, you are bold. Ignorance is always bold; knowledge hesitates. And the more you know, the more you feel that the ground underneath is dissolving. The more you know, the more you feel how ignorant you are.

Knowledge slowly builds up what Ignorance in an hour pulls down

To know that you do not know is the best.
To think you know when you do not is a disease.
Recognizing this disease as a disease is to be free of it.

It is harder to conceal ignorance than to acquire knowledge.

A little knowledge is a dangerous thing. So is a lot.