There are four sorts of people in this world.

There are those who know not, and know not that they know not.
They are fools, shun them.

There are those who know not, and know that they know not.
They are simple, teach them.

There are those who know, and know not that they know.
They are lost, guide them.

Then there are those who know, and know that they know.
They are wise, follow them.