Can you explain why the quotation mark was in putted on this sentence: "Notice,"the professor told the class, "Cassius' choice of imagery when he asks, 'Upon what meat doth this our Ceasar feed that he is grown so great?"

Answer 1

You miscopied the last part --
he is grown so great?'"

Study this site carefully for an explanation of quotation marks.

http://grammar.ccc.commnet.edu/grammar/marks/quotation.htm