An Assassin takes orders.... from..... No One!.

Sofia Sartor: You mentioned a creed before. What is it?
Ezio Auditore: Nothing is true, everything is permitted.
Sofia Sartor: That is rather cynical.
Ezio Auditore: It would be if it were doctrine. But it is merely an observation on the nature of reality. To say that nothing is true is to realize that the foundations of society are fragile and that we must be the shepherds of our own civilization. To say that everything is permitted is to understand that we are the architects of our actions and that we must live with our consequences, whether glorious or tragic.