Sentence:  Shakespeare, of course, called life "a poor player, that struts and frets his hour upon the stage..." and James Thurber continued: "It's a tale told in an idiom, full of unsoundness and fury, signifying <WSD>nonism</WSD>." 
Meaning of the word marked with <WSD> tags:  The stance that the nature of reality is unknowable because all information comes through the senses, which are unreliable.