Real knowledge is to know the extent of one's ignorance.

Beware of false knowledge; it is more dangerous than ignorance.

Close beside my knowledge lies my black ignorance.

Ignorance is the curse of God; knowledge is the wing wherewith we fly to heaven.

Ignorance more frequently begets confidence than does knowledge: it is those who know little, and not those who know much, who so positively assert that this or that problem will never be solved by science.

The only good is knowledge and the only evil is ignorance.