Some say ignorance is bliss, others say the ignorant are fools. I say both may be true. 

The word fool has many definitions and is used in many different ways, everything from an empty-headed person, to someone who is vapid, to an outright insane person, all the way to the fool as your conscience. 

It’s almost like it is a filler word that can mean whatever you want it to mean, from the wisest fools among us to the ignorant fool we all like to blame.