what causes king lears madness

Really it is some of Lear's children and his own stubbornness which cause his downfall. The reasons which justify his serious plunge into insanity are many as the audience is privy to the actions of his daughters and the indignity he has been shown since giving up his title which could easily drop an old proud former king into madness. The horrific action of all but two children in the play, Cordelia and Edgar, is summed up in a neat sentence by Gloucester as he enters the hovel to speak to Lear. He cries, "Our flesh and blood, my lord, is grown so vile/ That it doth hate what gets it" (III.4.136-137). The vileness, the evil, of Lear's two daughters and of Edmund (though ironically, at this point Gloucester is still speaking of Edgar) is such a betrayal that it has made the skin crawl and wish to reject the beings it helped to create.