Man isn't a fool for his ignorance, but rather for believing things that are wrong.
Habits are like the wrinkles on a man's brow; if you will smooth out the one, I will smooth out the other.
People who have nothing to say are never at a loss in talking.
It's not ignorance does so much damage; it's knowin' so derned much that ain't so.
Error will slip through a crack, while truth will stick in a doorway.
Stupidity,--unconscious ignorance.