What reaction does Macbeth display in Act V, scene 5, lines 17-28, when he learns of his wife's death?(What has been ultimately responsible for his...

In Scene 5 of Act V, when Macbeth learns of Lady Macbeth's death, he reflects

She should have died hereafter/There would have been a time for such a word.(V,v,17-18).

He rues that his wife has died now when he is still essaying to secure his position as King of Scotland.  Without Lady Macbeth, he realizes that much of the meaning to his aspirations of power is now gone. And, with Lady Macbeth's death, Macbeth himself becomes very conscious of his own mortality, a mortality that is, in the end, fairly insignificant:

Life's but a walking shadow, a poor player/That struts and frets his hour upon the stage/And then in heard no more...(V,v,26-28)

Macbeth compares life to the shadow of a "brief candle" that burns out quickly.  A person's life is only important to a few; otherwise, it is a mere

tale/Told by an idiot, full of sound and fury/Signifying nothing. (V,v,27-29)

These last two lines were vivid enough to the great American writer, William Faulkner, that he titled one of his best novels "The Sound and the Fury" because of the realtionships of the characters in the narrative, and because the first part of the book narrated by the very mentally challenged Benjamin is a "tale told by an idiot,"