You know nothing until you realize that.

Ignorance, when voluntary, is criminal, and a man may be properly charged with that evil which he neglected or refused to learn how to prevent.

Humor can get in under the door while seriousness is still fumbling at the handle.

He who knows ignorance well shall least know understanding well; he who knows understanding well shall surely know and understand ignorance well

all appears to change when we change

Mankind have a great aversion to intellectual labor; but even supposing knowledge to be easily attainable, more people would be content to be ignorant than would take even a little trouble to acquire it