The problem ain't what people know. It's what people know that ain't so that's the problem.

Facts...are stubborn things...

Very many maintain that all we know is still infinitely less than all that still remains unknown.

The more you know, the more you know you don't know.

Nothing is so firmly believed as that which we least know.

much of what other people know isn’t worth knowing.

Many are stubborn in pursuit of the path they have chosen. Few in pursuit of the goal.

Stubbornly persist, and you will find that the limits of your stubbornness go well beyond the stubbornness of your limits.

Nothing is so firmly believed as that which is least known.

But you perceive, my boy, that it is not so, and that facts, as usual, are very stubborn things, overruling all theories.

Ignorance is bold, and knowledge is reserved

People would rather believe than know.

The hardest thing to explain is the glaringly evident which everybody has decided not to see

Only a few know, how much one must know to know how little one knows.