What is the significances of Fool?

Lear's Fool

The hired court Fool, he attends Lear regularly and points out the truths which are missed or ignored. Upset by Cordelia's banishment, he ridicules Lear for being foolish enough to banish the good daughter and trust the evil ones. He further mocks his decision to give up his authority so fully. Once Lear goes mad, the Fool seems incredibly sane, making Lear remain dressed and playing along with his ideas of a trial versus Goneril and Regan.