Shakespeare's 400th

Accidentally gave myself a link to Hildarose's theme for today, the 400th anniversary of the birth and death of William Shakespeare.  I am not familiar with a lot of his work, but I did study Macbeth for my English Literature O level many years ago.  I wonder if you can see the connection to a quote from the play..............

LADY MACBETH
Out, damned spot! Out, I say!—One, two. Why, then, ’tis time to do ’t. Hell is murky!—Fie, my lord, fie! A soldier, and afeard? What need we fear who knows it, when none can call our power to account?—Yet who would have thought the old man to have had so much blood in him.