Kinds of ignorance

The state of thoroughly conscious ignorance which is the prelude to every advance in knowledge.James Clark Maxwell

Common ignorance is simply not having learned (or having forgotten) that which is known by others.

There is a pernicious ignorance which is found where someone not only fails to realize that he does not know, but mistakenly believes he knows something which is not true.

There is normal scientific ignorance, as each new scientific finding tends to raise new questions in effect adding new areas of proximate ignorance to be explored.

I was like a boy playing on the sea-shore, and diverting myself now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.Isaac Newton

Then there is Newtonian ignorance, all that not only don't we know but that we can not yet imagine as being knowable.