Discuss sight and sight within King Lear

In Shakespeare's tragedy King Lear, there is a reoccurring theme of insight and sight mostly between Gloucester and Lear; furthermore, Gloucester lacked physical sight but had insight, while Lear had physical sight but lacked insight. It is obvious that insight is not in any way derived from vision.
Throughout most of King Lear, Lear's vision is obstructed by his lack of insight. Since he can not see into other people's characters, he can not see them for who they really are. When Lear was angered by Cordelia in the beginning of the play, Kent tries to calm King Lear down but Lear say…