I still wonder about what prompts Lear’s death at the end of the play. One interpretation is…

I still wonder about what prompts Lear’s death at the end of the play. One interpretation is that he dies from unbearable joy induced by the belief that Cordelia is alive. But if he dies from joy thinking that Cordelia still lives he dies, unlike all other tragic heroes, not aware that any tragedy has taken place for the other deaths are not in the full sense tragic.  Then again, if we consider that Lear is mad once again at the end of the play, it again loses its tragedy for Lear becomes a man who has experienced everything and learned nothing.  To make him a tragic hero he must gain knowledge.  Does he?  And in what lines–at the end of the play, not part way through it?