All I really know is the extent of my own ignorance

I know nothing except the fact of my ignorance.

Ignorance is bold, and knowledge is reserved

I wish I was ignorant, so I didn't know how ignorant I am

My ignorance was inexcusable, and it made me ashamed.

My ignorance is not charming.

It takes considerable knowledge just to realize the extent of your own ignorance.

Our knowledge is a receding mirage in an expanding desert of ignorance.

Acquaint yourself with your own ignorance.

The doorstep to the temple of wisdom is a knowledge of our own ignorance.

is necessarily limited by his lack of knowledge of the circumstances

Surely this is the objectionable kind of ignorance, to think one knows what one does not know? But in this, gentlemen, here also perhaps I am different from the general run of mankind, and if I should claim to be wiser than someone in something it would be in this, that as I do not know well enough about what happens in the house of Hades, so I do not think I know.

I am likely to be wiser than he to this small, extent, that I do not think I know what I do not know.

The degree of ignorance cannot easily be expressed. We may say, for instance, that nearly two-thirds of them cannot read or write. This but partially expresses the fact. They are ignorant of the world about them, of modern economic organization, of the function of government, of individual worth and possibilities, — of nearly all those things which slavery in self-defence had to keep them from learning. Much that the white boy imbibes from his earliest social atmosphere forms the puzzling problems of the black boy’s mature years. America is not another word for Opportunity to all her sons.