In Death of a Salesman. explain why Ben is a symbol of success to Willy.

Ben is seen as a success because he is everything that
Willy is not.  Ben is adventuresome, larger than life, and above all, rich.  Ben
accomplishes what he sets out to do and is depicted in Willy's mind as someone that is
able to bend life to his own will.  This is not Willy, by any stretch of the
imagination.  Willy's imaginative conversations with Ben help to enhance the
apotheosized image of the older brother in the younger brother's mind.  In this light,
Ben does not have to endure the struggles that Willy endures and his statement of
emerging from the jungle as "rich" confirms in Willy's mind that being like Ben,
approaching life like him, and acting like him is what defines success.  Willy is the
diametric opposite of Ben and this is what makes him envy and covet him more.  Ben is
not shown in a realistic light because he is not a realistic vision.  Rather, Willy uses
Ben as an idolized and idealized notion of the good.