<P> The popular form of the expression is a derivative of a line in William Shakespeare 's play The Merchant of Venice , which employs the word `` glisters , '' a 17th - century synonym for `` glitters . '' The line comes from a secondary plot of the play , the puzzle of Portia 's boxes ( Act II - Scene VII - Prince of Morocco ) : </P>
who says all that glitters is not gold in the merchant of venice
Prince of Morocco